diff --git a/core-groovy/src/test/groovy/com/baeldung/stringtypes/CharacterInGroovy.groovy b/core-groovy/src/test/groovy/com/baeldung/stringtypes/CharacterInGroovy.groovy
new file mode 100644
index 0000000000..c043723d95
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/stringtypes/CharacterInGroovy.groovy
@@ -0,0 +1,19 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class CharacterInGroovy {
+
+    @Test
+    void 'character'() {
+        char a = 'A' as char
+        char b = 'B' as char
+        char c = (char) 'C'
+
+        Assert.assertTrue(a instanceof Character)
+        Assert.assertTrue(b instanceof Character)
+        Assert.assertTrue(c instanceof Character)
+    }
+
+}
diff --git a/core-groovy/src/test/groovy/com/baeldung/stringtypes/DollarSlashyString.groovy b/core-groovy/src/test/groovy/com/baeldung/stringtypes/DollarSlashyString.groovy
new file mode 100644
index 0000000000..db8ba68c8f
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/stringtypes/DollarSlashyString.groovy
@@ -0,0 +1,24 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Test
+
+class DollarSlashyString {
+
+    @Test
+    void 'dollar slashy string'() {
+        def name = "John"
+
+        def dollarSlashy = $/
+            Hello $name!,
+
+            I can show you $ sign or escaped dollar sign: $$ 
+            Both slashes works: \ or /, but we can still escape it: $/
+            
+            We have to escape opening and closing delimiter:
+            - $$$/  
+            - $/$$
+        /$
+
+        print(dollarSlashy)
+    }
+}
diff --git a/core-groovy/src/test/groovy/com/baeldung/stringtypes/DoubleQuotedString.groovy b/core-groovy/src/test/groovy/com/baeldung/stringtypes/DoubleQuotedString.groovy
new file mode 100644
index 0000000000..a730244d0a
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/stringtypes/DoubleQuotedString.groovy
@@ -0,0 +1,67 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class DoubleQuotedString {
+
+    @Test
+    void 'escape double quoted string'() {
+        def example = "Hello \"world\"!"
+
+        println(example)
+    }
+
+    @Test
+    void 'String ang GString'() {
+        def string = "example"
+        def stringWithExpression = "example${2}"
+
+        Assert.assertTrue(string instanceof String)
+        Assert.assertTrue(stringWithExpression instanceof GString)
+        Assert.assertTrue(stringWithExpression.toString() instanceof String)
+    }
+
+    @Test
+    void 'placeholder with variable'() {
+        def name = "John"
+        def helloName = "Hello $name!".toString()
+
+        Assert.assertEquals("Hello John!", helloName)
+    }
+
+    @Test
+    void 'placeholder with expression'() {
+        def result = "result is ${2 * 2}".toString()
+
+        Assert.assertEquals("result is 4", result)
+    }
+
+    @Test
+    void 'placeholder with dotted access'() {
+        def person = [name: 'John']
+
+        def myNameIs = "I'm $person.name, and you?".toString()
+
+        Assert.assertEquals("I'm John, and you?", myNameIs)
+    }
+
+    @Test
+    void 'placeholder with method call'() {
+        def name = 'John'
+
+        def result = "Uppercase name: ${name.toUpperCase()}".toString()
+
+        Assert.assertEquals("Uppercase name: JOHN", result)
+    }
+
+
+    @Test
+    void 'GString and String hashcode'() {
+        def string = "2+2 is 4"
+        def gstring = "2+2 is ${4}"
+
+        Assert.assertTrue(string.hashCode() != gstring.hashCode())
+    }
+
+}
diff --git a/core-groovy/src/test/groovy/com/baeldung/stringtypes/SingleQuotedString.groovy b/core-groovy/src/test/groovy/com/baeldung/stringtypes/SingleQuotedString.groovy
new file mode 100644
index 0000000000..569991b788
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/stringtypes/SingleQuotedString.groovy
@@ -0,0 +1,15 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class SingleQuotedString {
+
+    @Test
+    void 'single quoted string'() {
+        def example = 'Hello world'
+
+        Assert.assertEquals('Hello world!', 'Hello' + ' world!')
+    }
+
+}
diff --git a/core-groovy/src/test/groovy/com/baeldung/stringtypes/SlashyString.groovy b/core-groovy/src/test/groovy/com/baeldung/stringtypes/SlashyString.groovy
new file mode 100644
index 0000000000..09ba35e17e
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/stringtypes/SlashyString.groovy
@@ -0,0 +1,31 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class SlashyString {
+
+    @Test
+    void 'slashy string'() {
+        def pattern = /.*foobar.*\/hello.*/
+
+        Assert.assertTrue("I'm matching foobar /hello regexp pattern".matches(pattern))
+    }
+
+    void 'wont compile'() {
+//        if ('' == //) {
+//            println("I can't compile")
+//        }
+    }
+
+    @Test
+    void 'interpolate and multiline'() {
+        def name = 'John'
+
+        def example = /
+            Hello $name
+            second line        
+        /
+    }
+
+}
diff --git a/core-groovy/src/test/groovy/com/baeldung/stringtypes/Strings.groovy b/core-groovy/src/test/groovy/com/baeldung/stringtypes/Strings.groovy
new file mode 100644
index 0000000000..e45f352285
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/stringtypes/Strings.groovy
@@ -0,0 +1,26 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class Strings {
+
+    @Test
+    void 'string interpolation '() {
+        def name = "Kacper"
+
+        def result = "Hello ${name}!"
+
+        Assert.assertEquals("Hello Kacper!", result.toString())
+    }
+
+    @Test
+    void 'string concatenation'() {
+        def first = "first"
+        def second = "second"
+
+        def concatenation = first + second
+
+        Assert.assertEquals("firstsecond", concatenation)
+    }
+}
diff --git a/core-groovy/src/test/groovy/com/baeldung/stringtypes/TripleDoubleQuotedString.groovy b/core-groovy/src/test/groovy/com/baeldung/stringtypes/TripleDoubleQuotedString.groovy
new file mode 100644
index 0000000000..cbbb1a4665
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/stringtypes/TripleDoubleQuotedString.groovy
@@ -0,0 +1,19 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Test
+
+class TripleDoubleQuotedString {
+
+    @Test
+    void 'triple-quoted strings with interpolation'() {
+        def name = "John"
+
+        def multiLine = """
+            I'm $name.
+            "This is quotation"
+        """
+
+        println(multiLine)
+    }
+
+}
diff --git a/core-groovy/src/test/groovy/com/baeldung/stringtypes/TripleSingleQuotedString.groovy b/core-groovy/src/test/groovy/com/baeldung/stringtypes/TripleSingleQuotedString.groovy
new file mode 100644
index 0000000000..24d55b8a2a
--- /dev/null
+++ b/core-groovy/src/test/groovy/com/baeldung/stringtypes/TripleSingleQuotedString.groovy
@@ -0,0 +1,67 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class TripleSingleQuotedString {
+
+    def 'formatted json'() {
+        def jsonContent = '''
+        {
+            "name": "John",
+            "age": 20,
+            "birthDate": null
+        }
+        '''
+    }
+
+    def 'triple single quoted'() {
+        def triple = '''im triple single quoted string'''
+    }
+
+    @Test
+    void 'triple single quoted with multiline string'() {
+        def triple = '''
+            firstline
+            secondline
+        '''
+
+        Assert.assertTrue(triple.startsWith("\n"))
+    }
+
+    @Test
+    void 'triple single quoted with multiline string with stripIndent() and removing newline characters'() {
+        def triple = '''\
+            firstline
+            secondline'''.stripIndent()
+
+        Assert.assertEquals("firstline\nsecondline", triple)
+    }
+
+    @Test
+    void 'triple single quoted with multiline string with last line with only whitespaces'() {
+        def triple = '''\
+            firstline
+                secondline\
+        '''.stripIndent()
+
+        println(triple)
+    }
+
+    @Test
+    void 'triple single quoted with multiline string with stripMargin(Character) and removing newline characters'() {
+        def triple = '''\
+            |firstline
+            |secondline'''.stripMargin()
+
+        println(triple)
+    }
+
+    @Test
+    void 'striple single quoted with special characters'() {
+        def specialCharacters = '''hello \'John\'. This is backslash - \\. \nSecond line starts here'''
+
+        println(specialCharacters)
+    }
+
+}
diff --git a/core-java-11/src/main/java/com/baeldung/java11/httpclient/HttpClientExample.java b/core-java-11/src/main/java/com/baeldung/java11/httpclient/HttpClientExample.java
new file mode 100644
index 0000000000..fb4abd3bb6
--- /dev/null
+++ b/core-java-11/src/main/java/com/baeldung/java11/httpclient/HttpClientExample.java
@@ -0,0 +1,132 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package com.baeldung.java11.httpclient;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpClient.Version;
+import java.net.http.HttpRequest;
+import java.net.http.HttpRequest.BodyPublishers;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+import java.net.http.HttpResponse.PushPromiseHandler;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+public class HttpClientExample {
+
+    public static void main(String[] args) throws Exception {
+        httpGetRequest();
+        httpPostRequest();
+        asynchronousGetRequest();
+        asynchronousMultipleRequests();
+        pushRequest();
+    }
+
+    public static void httpGetRequest() throws URISyntaxException, IOException, InterruptedException {
+        HttpClient client = HttpClient.newHttpClient();
+        HttpRequest request = HttpRequest.newBuilder()
+            .version(HttpClient.Version.HTTP_2)
+            .uri(URI.create("http://jsonplaceholder.typicode.com/posts/1"))
+            .headers("Accept-Enconding", "gzip, deflate")
+            .build();
+        HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
+
+        String responseBody = response.body();
+        int responseStatusCode = response.statusCode();
+
+        System.out.println("httpGetRequest: " + responseBody);
+        System.out.println("httpGetRequest status code: " + responseStatusCode);
+    }
+
+    public static void httpPostRequest() throws URISyntaxException, IOException, InterruptedException {
+        HttpClient client = HttpClient.newBuilder()
+            .version(HttpClient.Version.HTTP_2)
+            .build();
+        HttpRequest request = HttpRequest.newBuilder(new URI("http://jsonplaceholder.typicode.com/posts"))
+            .version(HttpClient.Version.HTTP_2)
+            .POST(BodyPublishers.ofString("Sample Post Request"))
+            .build();
+        HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
+        String responseBody = response.body();
+        System.out.println("httpPostRequest : " + responseBody);
+    }
+
+    public static void asynchronousGetRequest() throws URISyntaxException {
+        HttpClient client = HttpClient.newHttpClient();
+        URI httpURI = new URI("http://jsonplaceholder.typicode.com/posts/1");
+        HttpRequest request = HttpRequest.newBuilder(httpURI)
+            .version(HttpClient.Version.HTTP_2)
+            .build();
+        CompletableFuture<Void> futureResponse = client.sendAsync(request, HttpResponse.BodyHandlers.ofString())
+            .thenAccept(resp -> {
+                System.out.println("Got pushed response " + resp.uri());
+                System.out.println("Response statuscode: " + resp.statusCode());
+                System.out.println("Response body: " + resp.body());
+            });
+        System.out.println("futureResponse" + futureResponse);
+
+    }
+
+    public static void asynchronousMultipleRequests() throws URISyntaxException {
+        HttpClient client = HttpClient.newHttpClient();
+        List<URI> uris = Arrays.asList(new URI("http://jsonplaceholder.typicode.com/posts/1"), new URI("http://jsonplaceholder.typicode.com/posts/2"));
+        List<HttpRequest> requests = uris.stream()
+            .map(HttpRequest::newBuilder)
+            .map(reqBuilder -> reqBuilder.build())
+            .collect(Collectors.toList());
+        System.out.println("Got pushed response1 " + requests);
+        CompletableFuture.allOf(requests.stream()
+            .map(request -> client.sendAsync(request, BodyHandlers.ofString()))
+            .toArray(CompletableFuture<?>[]::new))
+            .thenAccept(System.out::println)
+            .join();
+    }
+
+    public static void pushRequest() throws URISyntaxException, InterruptedException {
+        System.out.println("Running HTTP/2 Server Push example...");
+
+        HttpClient httpClient = HttpClient.newBuilder()
+            .version(Version.HTTP_2)
+            .build();
+
+        HttpRequest pageRequest = HttpRequest.newBuilder()
+            .uri(URI.create("https://http2.golang.org/serverpush"))
+            .build();
+
+        // Interface HttpResponse.PushPromiseHandler<T>
+        // void applyPushPromise​(HttpRequest initiatingRequest, HttpRequest pushPromiseRequest, Function<HttpResponse.BodyHandler<T>,​CompletableFuture<HttpResponse<T>>> acceptor)
+        httpClient.sendAsync(pageRequest, BodyHandlers.ofString(), pushPromiseHandler())
+            .thenAccept(pageResponse -> {
+                System.out.println("Page response status code: " + pageResponse.statusCode());
+                System.out.println("Page response headers: " + pageResponse.headers());
+                String responseBody = pageResponse.body();
+                System.out.println(responseBody);
+            }).join();
+
+        Thread.sleep(1000); // waiting for full response
+    }
+
+    private static PushPromiseHandler<String> pushPromiseHandler() {
+        return (HttpRequest initiatingRequest, 
+            HttpRequest pushPromiseRequest, 
+            Function<HttpResponse.BodyHandler<String>, 
+            CompletableFuture<HttpResponse<String>>> acceptor) -> {
+            acceptor.apply(BodyHandlers.ofString())
+                .thenAccept(resp -> {
+                    System.out.println(" Pushed response: " + resp.uri() + ", headers: " + resp.headers());
+                });
+            System.out.println("Promise request: " + pushPromiseRequest.uri());
+            System.out.println("Promise request: " + pushPromiseRequest.headers());
+        };
+    }
+
+}
diff --git a/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpClientTest.java b/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpClientTest.java
new file mode 100644
index 0000000000..bade666636
--- /dev/null
+++ b/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpClientTest.java
@@ -0,0 +1,240 @@
+package com.baeldung.java11.httpclient.test;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.io.IOException;
+import java.net.Authenticator;
+import java.net.CookieManager;
+import java.net.CookiePolicy;
+import java.net.HttpURLConnection;
+import java.net.PasswordAuthentication;
+import java.net.ProxySelector;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.Test;
+
+public class HttpClientTest {
+
+    @Test
+    public void shouldReturnSampleDataContentWhenConnectViaSystemProxy() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofString("Sample body"))
+            .build();
+      
+        
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .proxy(ProxySelector.getDefault())
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+        
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample body"));
+    }
+
+    @Test
+    public void shouldNotFollowRedirectWhenSetToDefaultNever() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("http://stackoverflow.com"))
+            .version(HttpClient.Version.HTTP_1_1)
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_MOVED_PERM));
+        assertThat(response.body(), containsString("https://stackoverflow.com/"));
+    }
+
+    @Test
+    public void shouldFollowRedirectWhenSetToAlways() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("http://stackoverflow.com"))
+            .version(HttpClient.Version.HTTP_1_1)
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .followRedirects(HttpClient.Redirect.ALWAYS)
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.request()
+            .uri()
+            .toString(), equalTo("https://stackoverflow.com/"));
+    }
+
+    @Test
+    public void shouldReturnOKStatusForAuthenticatedAccess() throws URISyntaxException, IOException, InterruptedException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/basic-auth"))
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .authenticator(new Authenticator() {
+                @Override
+                protected PasswordAuthentication getPasswordAuthentication() {
+                    return new PasswordAuthentication("postman", "password".toCharArray());
+                }
+            })
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldSendRequestAsync() throws URISyntaxException, InterruptedException, ExecutionException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofString("Sample body"))
+            .build();
+        CompletableFuture<HttpResponse<String>> response = HttpClient.newBuilder()
+            .build()
+            .sendAsync(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.get()
+            .statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldUseJustTwoThreadWhenProcessingSendAsyncRequest() throws URISyntaxException, InterruptedException, ExecutionException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .GET()
+            .build();
+
+        ExecutorService executorService = Executors.newFixedThreadPool(2);
+
+        CompletableFuture<HttpResponse<String>> response1 = HttpClient.newBuilder()
+            .executor(executorService)
+            .build()
+            .sendAsync(request, HttpResponse.BodyHandlers.ofString());
+
+        CompletableFuture<HttpResponse<String>> response2 = HttpClient.newBuilder()
+            .executor(executorService)
+            .build()
+            .sendAsync(request, HttpResponse.BodyHandlers.ofString());
+
+        CompletableFuture<HttpResponse<String>> response3 = HttpClient.newBuilder()
+            .executor(executorService)
+            .build()
+            .sendAsync(request, HttpResponse.BodyHandlers.ofString());
+
+        CompletableFuture.allOf(response1, response2, response3)
+            .join();
+
+        assertThat(response1.get()
+            .statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response2.get()
+            .statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response3.get()
+            .statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldNotStoreCookieWhenPolicyAcceptNone() throws URISyntaxException, IOException, InterruptedException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .GET()
+            .build();
+
+        HttpClient httpClient = HttpClient.newBuilder()
+            .cookieHandler(new CookieManager(null, CookiePolicy.ACCEPT_NONE))
+            .build();
+
+        httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertTrue(httpClient.cookieHandler()
+            .isPresent());
+    }
+
+    @Test
+    public void shouldStoreCookieWhenPolicyAcceptAll() throws URISyntaxException, IOException, InterruptedException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .GET()
+            .build();
+
+        HttpClient httpClient = HttpClient.newBuilder()
+            .cookieHandler(new CookieManager(null, CookiePolicy.ACCEPT_ALL))
+            .build();
+
+        httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertTrue(httpClient.cookieHandler()
+            .isPresent());
+    }
+
+    @Test
+    public void shouldProcessMultipleRequestViaStream() throws URISyntaxException, ExecutionException, InterruptedException {
+        List<URI> targets = Arrays.asList(new URI("https://postman-echo.com/get?foo1=bar1"), new URI("https://postman-echo.com/get?foo2=bar2"));
+
+        HttpClient client = HttpClient.newHttpClient();
+
+        List<CompletableFuture<String>> futures = targets.stream()
+            .map(target -> client.sendAsync(HttpRequest.newBuilder(target)
+                .GET()
+                .build(), HttpResponse.BodyHandlers.ofString())
+                .thenApply(response -> response.body()))
+            .collect(Collectors.toList());
+
+        CompletableFuture.allOf(futures.toArray(new CompletableFuture[0]))
+            .join();
+
+        if (futures.get(0)
+            .get()
+            .contains("foo1")) {
+            assertThat(futures.get(0)
+                .get(), containsString("bar1"));
+            assertThat(futures.get(1)
+                .get(), containsString("bar2"));
+        } else {
+            assertThat(futures.get(1)
+                .get(), containsString("bar2"));
+            assertThat(futures.get(1)
+                .get(), containsString("bar1"));
+        }
+
+    }
+    
+    @Test
+    public void completeExceptionallyExample() {
+        CompletableFuture<String> cf = CompletableFuture.completedFuture("message").thenApplyAsync(String::toUpperCase,
+                CompletableFuture.delayedExecutor(1, TimeUnit.SECONDS));
+        CompletableFuture<String> exceptionHandler = cf.handle((s, th) -> { return (th != null) ? "message upon cancel" : ""; });
+        cf.completeExceptionally(new RuntimeException("completed exceptionally"));
+        assertTrue("Was not completed exceptionally", cf.isCompletedExceptionally());
+        try {
+            cf.join();
+            fail("Should have thrown an exception");
+        } catch (CompletionException ex) { // just for testing
+            assertEquals("completed exceptionally", ex.getCause().getMessage());
+        }
+
+        assertEquals("message upon cancel", exceptionHandler.join());
+    }
+
+}
diff --git a/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpRequestTest.java b/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpRequestTest.java
new file mode 100644
index 0000000000..7d138bd8d5
--- /dev/null
+++ b/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpRequestTest.java
@@ -0,0 +1,168 @@
+package com.baeldung.java11.httpclient.test;
+
+import static java.time.temporal.ChronoUnit.SECONDS;
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.nio.file.Paths;
+import java.security.NoSuchAlgorithmException;
+import java.time.Duration;
+
+import org.junit.Test;
+
+public class HttpRequestTest {
+
+    @Test
+    public void shouldReturnStatusOKWhenSendGetRequest() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldUseHttp2WhenWebsiteUsesHttp2() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://stackoverflow.com"))
+            .version(HttpClient.Version.HTTP_2)
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.version(), equalTo(HttpClient.Version.HTTP_2));
+    }
+
+    @Test
+    public void shouldFallbackToHttp1_1WhenWebsiteDoesNotUseHttp2() throws IOException, InterruptedException, URISyntaxException, NoSuchAlgorithmException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .version(HttpClient.Version.HTTP_2)
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.version(), equalTo(HttpClient.Version.HTTP_1_1));
+    }
+
+    @Test
+    public void shouldReturnStatusOKWhenSendGetRequestWithDummyHeaders() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .headers("key1", "value1", "key2", "value2")
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldReturnStatusOKWhenSendGetRequestTimeoutSet() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .timeout(Duration.of(10, SECONDS))
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldReturnNoContentWhenPostWithNoBody() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .POST(HttpRequest.BodyPublishers.noBody())
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldReturnSampleDataContentWhenPostWithBodyText() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofString("Sample request body"))
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample request body"));
+    }
+
+    @Test
+    public void shouldReturnSampleDataContentWhenPostWithInputStream() throws IOException, InterruptedException, URISyntaxException {
+        byte[] sampleData = "Sample request body".getBytes();
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofInputStream(() -> new ByteArrayInputStream(sampleData)))
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample request body"));
+    }
+
+    @Test
+    public void shouldReturnSampleDataContentWhenPostWithByteArrayProcessorStream() throws IOException, InterruptedException, URISyntaxException {
+        byte[] sampleData = "Sample request body".getBytes();
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofByteArray(sampleData))
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample request body"));
+    }
+
+    @Test
+    public void shouldReturnSampleDataContentWhenPostWithFileProcessorStream() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofFile(Paths.get("src/test/resources/sample.txt")))
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample file content"));
+    }
+
+}
diff --git a/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpResponseTest.java b/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpResponseTest.java
new file mode 100644
index 0000000000..78d86fbf4e
--- /dev/null
+++ b/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpResponseTest.java
@@ -0,0 +1,54 @@
+package com.baeldung.java11.httpclient.test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+
+import org.junit.Test;
+
+public class HttpResponseTest {
+
+    @Test
+    public void shouldReturnStatusOKWhenSendGetRequest() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .version(HttpClient.Version.HTTP_2)
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .followRedirects(HttpClient.Redirect.NORMAL)
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertNotNull(response.body());
+    }
+
+    @Test
+    public void shouldResponseURIDifferentThanRequestUIRWhenRedirect() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("http://stackoverflow.com"))
+            .version(HttpClient.Version.HTTP_2)
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .followRedirects(HttpClient.Redirect.NORMAL)
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(request.uri()
+            .toString(), equalTo("http://stackoverflow.com"));
+        assertThat(response.uri()
+            .toString(), equalTo("https://stackoverflow.com/"));
+    }
+
+}
diff --git a/core-kotlin-2/.gitignore b/core-kotlin-2/.gitignore
new file mode 100644
index 0000000000..0c017e8f8c
--- /dev/null
+++ b/core-kotlin-2/.gitignore
@@ -0,0 +1,14 @@
+/bin/
+
+#ignore gradle
+.gradle/
+
+
+#ignore build and generated files
+build/
+node/
+out/
+
+#ignore installed node modules and package lock file
+node_modules/
+package-lock.json
diff --git a/core-kotlin-2/README.md b/core-kotlin-2/README.md
new file mode 100644
index 0000000000..ff12555376
--- /dev/null
+++ b/core-kotlin-2/README.md
@@ -0,0 +1 @@
+## Relevant articles:
diff --git a/core-kotlin-2/build.gradle b/core-kotlin-2/build.gradle
new file mode 100644
index 0000000000..b058e0ecad
--- /dev/null
+++ b/core-kotlin-2/build.gradle
@@ -0,0 +1,48 @@
+
+
+group 'com.baeldung.ktor'
+version '1.0-SNAPSHOT'
+
+
+buildscript {
+    ext.kotlin_version = '1.2.41'
+
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+apply plugin: 'java'
+apply plugin: 'kotlin'
+apply plugin: 'application'
+
+mainClassName = 'APIServer.kt'
+
+sourceCompatibility = 1.8
+compileKotlin { kotlinOptions.jvmTarget = "1.8" }
+compileTestKotlin { kotlinOptions.jvmTarget = "1.8" }
+
+kotlin { experimental { coroutines "enable" } }
+
+repositories {
+    mavenCentral()
+    jcenter()
+    maven { url "https://dl.bintray.com/kotlin/ktor" }
+}
+sourceSets {
+    main{
+        kotlin{
+            srcDirs 'com/baeldung/ktor'
+        }
+    }
+
+}
+
+dependencies {
+    compile "ch.qos.logback:logback-classic:1.2.1"
+    testCompile group: 'junit', name: 'junit', version: '4.12'
+}
\ No newline at end of file
diff --git a/core-kotlin-2/gradle/wrapper/gradle-wrapper.jar b/core-kotlin-2/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000000..01b8bf6b1f
Binary files /dev/null and b/core-kotlin-2/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/core-kotlin-2/gradle/wrapper/gradle-wrapper.properties b/core-kotlin-2/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000000..933b6473ce
--- /dev/null
+++ b/core-kotlin-2/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-bin.zip
diff --git a/core-kotlin-2/gradlew b/core-kotlin-2/gradlew
new file mode 100644
index 0000000000..cccdd3d517
--- /dev/null
+++ b/core-kotlin-2/gradlew
@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"
diff --git a/core-kotlin-2/gradlew.bat b/core-kotlin-2/gradlew.bat
new file mode 100644
index 0000000000..f9553162f1
--- /dev/null
+++ b/core-kotlin-2/gradlew.bat
@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/core-kotlin-2/pom.xml b/core-kotlin-2/pom.xml
new file mode 100644
index 0000000000..81df3cee81
--- /dev/null
+++ b/core-kotlin-2/pom.xml
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-kotlin-2</artifactId>
+    <name>core-kotlin-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-kotlin</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../parent-kotlin</relativePath>
+    </parent>
+
+</project>
diff --git a/core-kotlin-2/resources/logback.xml b/core-kotlin-2/resources/logback.xml
new file mode 100644
index 0000000000..9452207268
--- /dev/null
+++ b/core-kotlin-2/resources/logback.xml
@@ -0,0 +1,11 @@
+<configuration>
+  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+    <encoder>
+      <pattern>%d{YYYY-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
+    </encoder>
+  </appender>
+
+  <root level="INFO">
+    <appender-ref ref="STDOUT"/>
+  </root>
+</configuration>
\ No newline at end of file
diff --git a/core-kotlin-2/settings.gradle b/core-kotlin-2/settings.gradle
new file mode 100644
index 0000000000..c91c993971
--- /dev/null
+++ b/core-kotlin-2/settings.gradle
@@ -0,0 +1,2 @@
+rootProject.name = 'KtorWithKotlin'
+
diff --git a/core-kotlin-2/src/main/resources/logback.xml b/core-kotlin-2/src/main/resources/logback.xml
new file mode 100644
index 0000000000..7d900d8ea8
--- /dev/null
+++ b/core-kotlin-2/src/main/resources/logback.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>
\ No newline at end of file
diff --git a/core-kotlin/src/test/kotlin/com/baeldung/voidtypes/VoidTypesUnitTest.kt b/core-kotlin-2/src/test/kotlin/voidtypes/VoidTypesUnitTest.kt
similarity index 100%
rename from core-kotlin/src/test/kotlin/com/baeldung/voidtypes/VoidTypesUnitTest.kt
rename to core-kotlin-2/src/test/kotlin/voidtypes/VoidTypesUnitTest.kt
diff --git a/core-kotlin-2/src/test/resources/Kotlin.in b/core-kotlin-2/src/test/resources/Kotlin.in
new file mode 100644
index 0000000000..d140d4429e
--- /dev/null
+++ b/core-kotlin-2/src/test/resources/Kotlin.in
@@ -0,0 +1,5 @@
+Hello to Kotlin. Its:
+1. Concise
+2. Safe
+3. Interoperable
+4. Tool-friendly
\ No newline at end of file
diff --git a/core-kotlin-2/src/test/resources/Kotlin.out b/core-kotlin-2/src/test/resources/Kotlin.out
new file mode 100644
index 0000000000..63d15d2528
--- /dev/null
+++ b/core-kotlin-2/src/test/resources/Kotlin.out
@@ -0,0 +1,2 @@
+Kotlin
+Concise, Safe, Interoperable, Tool-friendly
\ No newline at end of file
diff --git a/core-kotlin/src/main/kotlin/com/baeldung/static/ConsoleUtils.kt b/core-kotlin/src/main/kotlin/com/baeldung/static/ConsoleUtils.kt
new file mode 100644
index 0000000000..23c7cfb11a
--- /dev/null
+++ b/core-kotlin/src/main/kotlin/com/baeldung/static/ConsoleUtils.kt
@@ -0,0 +1,10 @@
+package com.baeldung.static
+
+class ConsoleUtils {
+    companion object {
+        @JvmStatic
+        fun debug(debugMessage : String) {
+            println("[DEBUG] $debugMessage")
+        }
+    }
+}
\ No newline at end of file
diff --git a/core-kotlin/src/main/kotlin/com/baeldung/static/LoggingUtils.kt b/core-kotlin/src/main/kotlin/com/baeldung/static/LoggingUtils.kt
new file mode 100644
index 0000000000..e67addc9ea
--- /dev/null
+++ b/core-kotlin/src/main/kotlin/com/baeldung/static/LoggingUtils.kt
@@ -0,0 +1,5 @@
+package com.baeldung.static
+
+fun debug(debugMessage : String) {
+    println("[DEBUG] $debugMessage")
+}
\ No newline at end of file
diff --git a/core-kotlin/src/test/kotlin/com/baeldung/static/ConsoleUtilsUnitTest.kt b/core-kotlin/src/test/kotlin/com/baeldung/static/ConsoleUtilsUnitTest.kt
new file mode 100644
index 0000000000..8abed144eb
--- /dev/null
+++ b/core-kotlin/src/test/kotlin/com/baeldung/static/ConsoleUtilsUnitTest.kt
@@ -0,0 +1,10 @@
+package com.baeldung.static
+
+import org.junit.Test
+
+class ConsoleUtilsUnitTest {
+    @Test
+    fun givenAStaticMethod_whenCalled_thenNoErrorIsThrown() {
+        ConsoleUtils.debug("test message")
+    }
+}
\ No newline at end of file
diff --git a/core-kotlin/src/test/kotlin/com/baeldung/static/LoggingUtilsUnitTest.kt b/core-kotlin/src/test/kotlin/com/baeldung/static/LoggingUtilsUnitTest.kt
new file mode 100644
index 0000000000..59587ff009
--- /dev/null
+++ b/core-kotlin/src/test/kotlin/com/baeldung/static/LoggingUtilsUnitTest.kt
@@ -0,0 +1,10 @@
+package com.baeldung.static
+
+import org.junit.Test
+
+class LoggingUtilsUnitTest {
+    @Test
+    fun givenAPackageMethod_whenCalled_thenNoErrorIsThrown() {
+        debug("test message")
+    }
+}
\ No newline at end of file
diff --git a/java-collections-maps/src/test/java/com/baeldung/java/map/MultiValuedMapUnitTest.java b/java-collections-maps/src/test/java/com/baeldung/java/map/MultiValuedMapUnitTest.java
index 67e4a5b0a0..b02b67f685 100644
--- a/java-collections-maps/src/test/java/com/baeldung/java/map/MultiValuedMapUnitTest.java
+++ b/java-collections-maps/src/test/java/com/baeldung/java/map/MultiValuedMapUnitTest.java
@@ -22,139 +22,157 @@ public class MultiValuedMapUnitTest {
     public void givenMultiValuesMap_whenPuttingMultipleValuesUsingPutMethod_thenReturningAllValues() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
         
-        map.put("key", "value1");
-        map.put("key", "value2");
-        map.put("key", "value2");
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
         
-        assertThat((Collection<String>) map.get("key")).containsExactly("value1", "value2", "value2");
+        assertThat((Collection<String>) map.get("fruits")).containsExactly("apple", "orange");
+
     }
  
     @Test
     public void givenMultiValuesMap_whenPuttingMultipleValuesUsingPutAllMethod_thenReturningAllValues() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
+       
+        map.putAll("vehicles", Arrays.asList("car", "bike"));
         
-        map.putAll("key", Arrays.asList("value1", "value2", "value2"));
-        
-        assertThat((Collection<String>) map.get("key")).containsExactly("value1", "value2", "value2");
+        assertThat((Collection<String>) map.get("vehicles")).containsExactly("car", "bike");
+
     }
 
     @Test
     public void givenMultiValuesMap_whenGettingValueUsingGetMethod_thenReturningValue() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
+      
+        map.put("fruits", "apple");
         
-        assertThat((Collection<String>) map.get("key")).containsExactly("value");
+        assertThat((Collection<String>) map.get("fruits")).containsExactly("apple");
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingEntriesMethod_thenReturningMappings() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value1");
-        map.put("key", "value2");
-        
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+
         Collection<Entry<String, String>> entries = (Collection<Entry<String, String>>) map.entries();
         
         for(Map.Entry<String,String> entry : entries) {
-            assertThat(entry.getKey()).contains("key");
-            assertTrue(entry.getValue().equals("value1") || entry.getValue().equals("value2") );
+            assertThat(entry.getKey()).contains("fruits");
+            assertTrue(entry.getValue().equals("apple") || entry.getValue().equals("orange") );
         }
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingKeysMethod_thenReturningAllKeys() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
+
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
         
-        assertThat(((Collection<String>) map.keys())).contains("key", "key1", "key2");
+        assertThat(((Collection<String>) map.keys())).contains("fruits", "vehicles");
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingKeySetMethod_thenReturningAllKeys() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
+
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
         
-        assertThat((Collection<String>) map.keySet()).contains("key", "key1", "key2");
+        assertThat((Collection<String>) map.keySet()).contains("fruits", "vehicles");
+
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingValuesMethod_thenReturningAllValues() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
+
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
         
-        assertThat(((Collection<String>) map.values())).contains("value", "value1", "value2");
+        assertThat(((Collection<String>) map.values())).contains("apple", "orange", "car", "bike");
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingRemoveMethod_thenReturningUpdatedMap() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
-        assertThat(((Collection<String>) map.values())).contains("value", "value1", "value2");
+
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
+        assertThat(((Collection<String>) map.values())).contains("apple", "orange", "car", "bike");
         
-        map.remove("key");
+        map.remove("fruits");
         
-        assertThat(((Collection<String>) map.values())).contains("value1", "value2");
+        assertThat(((Collection<String>) map.values())).contains("car", "bike");
+
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingRemoveMappingMethod_thenReturningUpdatedMapAfterMappingRemoved() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
-        assertThat(((Collection<String>) map.values())).contains("value", "value1", "value2");
+
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
+        assertThat(((Collection<String>) map.values())).contains("apple", "orange", "car", "bike");
         
-        map.removeMapping("key", "value");
+        map.removeMapping("fruits", "apple");
         
-        assertThat(((Collection<String>) map.values())).contains("value1", "value2");
+        assertThat(((Collection<String>) map.values())).contains("orange", "car", "bike");
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingClearMethod_thenReturningEmptyMap() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
-        assertThat(((Collection<String>) map.values())).contains("value", "value1", "value2");
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
+        assertThat(((Collection<String>) map.values())).contains("apple", "orange", "car", "bike");
         
         map.clear();
-        
+  
         assertTrue(map.isEmpty());
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingContainsKeyMethod_thenReturningTrue() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
         
-        assertTrue(map.containsKey("key"));
+        assertTrue(map.containsKey("fruits"));
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingContainsValueMethod_thenReturningTrue() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
         
-        assertTrue(map.containsValue("value"));
+        assertTrue(map.containsValue("orange"));
     }
 
     @Test
     public void givenMultiValuesMap_whenUsingIsEmptyMethod_thenReturningFalse() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
         
         assertFalse(map.isEmpty());
     }
@@ -162,42 +180,42 @@ public class MultiValuedMapUnitTest {
     @Test
     public void givenMultiValuesMap_whenUsingSizeMethod_thenReturningElementCount() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value");
-        map.put("key1", "value1");
-        map.put("key2", "value2");
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("vehicles", "car");
+        map.put("vehicles", "bike");
         
-        assertEquals(3, map.size());
+        assertEquals(4, map.size());
     }
 
     @Test
     public void givenArrayListValuedHashMap_whenPuttingDoubleValues_thenReturningAllValues() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
+        map.put("fruits", "orange");
         
-        map.put("key", "value1");
-        map.put("key", "value2");
-        map.put("key", "value2");
-        
-        assertThat((Collection<String>) map.get("key")).containsExactly("value1", "value2", "value2");
+        assertThat((Collection<String>) map.get("fruits")).containsExactly("apple", "orange", "orange");
     }
 
     @Test
     public void givenHashSetValuedHashMap_whenPuttingTwiceTheSame_thenReturningOneValue() {
         MultiValuedMap<String, String> map = new HashSetValuedHashMap<>();
-        
-        map.put("key1", "value1");
-        map.put("key1", "value1");
-        
-        assertThat((Collection<String>) map.get("key1")).containsExactly("value1");
+        map.put("fruits", "apple");
+        map.put("fruits", "apple");
+  
+        assertThat((Collection<String>) map.get("fruits")).containsExactly("apple");
     }
 
     @Test(expected = UnsupportedOperationException.class)
     public void givenUnmodifiableMultiValuedMap_whenInserting_thenThrowingException() {
         MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();
-        map.put("key", "value1");
-        map.put("key", "value2");
+        map.put("fruits", "apple");
+        map.put("fruits", "orange");
         MultiValuedMap<String, String> immutableMap = MultiMapUtils.unmodifiableMultiValuedMap(map);
         
-        immutableMap.put("key", "value3");
+        immutableMap.put("fruits", "banana");
+
     }
     
 
diff --git a/persistence-modules/spring-data-jpa/pom.xml b/persistence-modules/spring-data-jpa/pom.xml
index 786e587734..401f4877ac 100644
--- a/persistence-modules/spring-data-jpa/pom.xml
+++ b/persistence-modules/spring-data-jpa/pom.xml
@@ -27,11 +27,27 @@
             <groupId>org.hibernate</groupId>
             <artifactId>hibernate-envers</artifactId>
         </dependency>
+
         <dependency>
             <groupId>com.h2database</groupId>
             <artifactId>h2</artifactId>
         </dependency>
 
+        <!-- Test containers only dependencies -->
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>postgresql</artifactId>
+            <version>1.10.6</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.postgresql</groupId>
+            <artifactId>postgresql</artifactId>
+            <version>42.2.5</version>
+        </dependency>
+        <!-- Test containers only dependencies -->
+
         <dependency>
             <groupId>org.springframework.security</groupId>
             <artifactId>spring-security-test</artifactId>
diff --git a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceConfiguration.java b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceConfiguration.java
index 2bdd4e5451..891624443b 100644
--- a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceConfiguration.java
+++ b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceConfiguration.java
@@ -1,14 +1,11 @@
 package com.baeldung.config;
 
-import java.util.Properties;
-
-import javax.sql.DataSource;
-
+import com.baeldung.dao.repositories.impl.ExtendedRepositoryImpl;
+import com.baeldung.services.IBarService;
+import com.baeldung.services.impl.BarSpringDataJpaService;
+import com.google.common.base.Preconditions;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.ComponentScan;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.PropertySource;
+import org.springframework.context.annotation.*;
 import org.springframework.core.env.Environment;
 import org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor;
 import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
@@ -21,10 +18,8 @@ import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
 import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.transaction.annotation.EnableTransactionManagement;
 
-import com.baeldung.dao.repositories.impl.ExtendedRepositoryImpl;
-import com.baeldung.services.IBarService;
-import com.baeldung.services.impl.BarSpringDataJpaService;
-import com.google.common.base.Preconditions;
+import javax.sql.DataSource;
+import java.util.Properties;
 
 @Configuration
 @ComponentScan({ "com.baeldung.dao", "com.baeldung.services" })
@@ -32,6 +27,7 @@ import com.google.common.base.Preconditions;
 @EnableJpaRepositories(basePackages = { "com.baeldung.dao" }, repositoryBaseClass = ExtendedRepositoryImpl.class)
 @EnableJpaAuditing
 @PropertySource("classpath:persistence.properties")
+@Profile("!tc")
 public class PersistenceConfiguration {
 
     @Autowired
diff --git a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceProductConfiguration.java b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceProductConfiguration.java
index 207fba9bc5..ecaee82ae5 100644
--- a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceProductConfiguration.java
+++ b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceProductConfiguration.java
@@ -4,6 +4,7 @@ import com.google.common.base.Preconditions;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Profile;
 import org.springframework.context.annotation.PropertySource;
 import org.springframework.core.env.Environment;
 import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
@@ -19,6 +20,7 @@ import java.util.HashMap;
 @Configuration
 @PropertySource({"classpath:persistence-multiple-db.properties"})
 @EnableJpaRepositories(basePackages = "com.baeldung.dao.repositories.product", entityManagerFactoryRef = "productEntityManager", transactionManagerRef = "productTransactionManager")
+@Profile("!tc")
 public class PersistenceProductConfiguration {
     @Autowired
     private Environment env;
diff --git a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceUserConfiguration.java b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceUserConfiguration.java
index dd32477755..6893d889e6 100644
--- a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceUserConfiguration.java
+++ b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/config/PersistenceUserConfiguration.java
@@ -2,10 +2,7 @@ package com.baeldung.config;
 
 import com.google.common.base.Preconditions;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.Primary;
-import org.springframework.context.annotation.PropertySource;
+import org.springframework.context.annotation.*;
 import org.springframework.core.env.Environment;
 import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
 import org.springframework.jdbc.datasource.DriverManagerDataSource;
@@ -20,6 +17,7 @@ import java.util.HashMap;
 @Configuration
 @PropertySource({"classpath:persistence-multiple-db.properties"})
 @EnableJpaRepositories(basePackages = "com.baeldung.dao.repositories.user", entityManagerFactoryRef = "userEntityManager", transactionManagerRef = "userTransactionManager")
+@Profile("!tc")
 public class PersistenceUserConfiguration {
     @Autowired
     private Environment env;
diff --git a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/dao/repositories/user/UserRepository.java b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/dao/repositories/user/UserRepository.java
index 7f54254832..c291f93e2c 100644
--- a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/dao/repositories/user/UserRepository.java
+++ b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/dao/repositories/user/UserRepository.java
@@ -1,7 +1,6 @@
 package com.baeldung.dao.repositories.user;
 
 import com.baeldung.domain.user.User;
-
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
@@ -21,13 +20,13 @@ public interface UserRepository extends JpaRepository<User, Integer> , UserRepos
     @Query("SELECT u FROM User u WHERE u.status = 1")
     Collection<User> findAllActiveUsers();
 
-    @Query(value = "SELECT * FROM USERS.USERS u WHERE u.status = 1", nativeQuery = true)
+    @Query(value = "SELECT * FROM Users u WHERE u.status = 1", nativeQuery = true)
     Collection<User> findAllActiveUsersNative();
 
     @Query("SELECT u FROM User u WHERE u.status = ?1")
     User findUserByStatus(Integer status);
 
-    @Query(value = "SELECT * FROM USERS.Users u WHERE u.status = ?1", nativeQuery = true)
+    @Query(value = "SELECT * FROM Users u WHERE u.status = ?1", nativeQuery = true)
     User findUserByStatusNative(Integer status);
 
     @Query("SELECT u FROM User u WHERE u.status = ?1 and u.name = ?2")
@@ -36,7 +35,7 @@ public interface UserRepository extends JpaRepository<User, Integer> , UserRepos
     @Query("SELECT u FROM User u WHERE u.status = :status and u.name = :name")
     User findUserByStatusAndNameNamedParams(@Param("status") Integer status, @Param("name") String name);
 
-    @Query(value = "SELECT * FROM USERS.Users u WHERE u.status = :status AND u.name = :name", nativeQuery = true)
+    @Query(value = "SELECT * FROM Users u WHERE u.status = :status AND u.name = :name", nativeQuery = true)
     User findUserByStatusAndNameNamedParamsNative(@Param("status") Integer status, @Param("name") String name);
 
     @Query("SELECT u FROM User u WHERE u.status = :status and u.name = :name")
@@ -48,7 +47,7 @@ public interface UserRepository extends JpaRepository<User, Integer> , UserRepos
     @Query("SELECT u FROM User u WHERE u.name like :name%")
     User findUserByNameLikeNamedParam(@Param("name") String name);
 
-    @Query(value = "SELECT * FROM USERS.users u WHERE u.name LIKE ?1%", nativeQuery = true)
+    @Query(value = "SELECT * FROM users u WHERE u.name LIKE ?1%", nativeQuery = true)
     User findUserByNameLikeNative(String name);
 
     @Query(value = "SELECT u FROM User u")
@@ -57,7 +56,7 @@ public interface UserRepository extends JpaRepository<User, Integer> , UserRepos
     @Query(value = "SELECT u FROM User u ORDER BY id")
     Page<User> findAllUsersWithPagination(Pageable pageable);
 
-    @Query(value = "SELECT * FROM USERS.Users ORDER BY id", countQuery = "SELECT count(*) FROM USERS.Users", nativeQuery = true)
+    @Query(value = "SELECT * FROM Users ORDER BY id", countQuery = "SELECT count(*) FROM Users", nativeQuery = true)
     Page<User> findAllUsersWithPaginationNative(Pageable pageable);
 
     @Modifying
@@ -65,6 +64,10 @@ public interface UserRepository extends JpaRepository<User, Integer> , UserRepos
     int updateUserSetStatusForName(@Param("status") Integer status, @Param("name") String name);
 
     @Modifying
-    @Query(value = "UPDATE USERS.Users u SET u.status = ? WHERE u.name = ?", nativeQuery = true)
+    @Query(value = "UPDATE Users u SET u.status = ? WHERE u.name = ?", nativeQuery = true)
     int updateUserSetStatusForNameNative(Integer status, String name);
+
+    @Modifying
+    @Query(value = "UPDATE Users u SET status = ? WHERE u.name = ?", nativeQuery = true)
+    int updateUserSetStatusForNameNativePostgres(Integer status, String name);
 }
diff --git a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/domain/user/Possession.java b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/domain/user/Possession.java
index 614e13df36..b1427c0270 100644
--- a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/domain/user/Possession.java
+++ b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/domain/user/Possession.java
@@ -1,13 +1,9 @@
 package com.baeldung.domain.user;
 
-import javax.persistence.Entity;
-import javax.persistence.GeneratedValue;
-import javax.persistence.GenerationType;
-import javax.persistence.Id;
-import javax.persistence.Table;
+import javax.persistence.*;
 
 @Entity
-@Table(schema = "users")
+@Table
 public class Possession {
 
     @Id
diff --git a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/domain/user/User.java b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/domain/user/User.java
index 3a8b617d9a..28c52140c7 100644
--- a/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/domain/user/User.java
+++ b/persistence-modules/spring-data-jpa/src/main/java/com/baeldung/domain/user/User.java
@@ -4,7 +4,7 @@ import javax.persistence.*;
 import java.util.List;
 
 @Entity
-@Table(name = "users", schema = "users")
+@Table(name = "users")
 public class User {
 
     @Id
diff --git a/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryCommon.java b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryCommon.java
new file mode 100644
index 0000000000..8c4e8073b7
--- /dev/null
+++ b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryCommon.java
@@ -0,0 +1,371 @@
+package com.baeldung.dao.repositories;
+
+import com.baeldung.dao.repositories.user.UserRepository;
+import com.baeldung.domain.user.User;
+import org.junit.After;
+import org.junit.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Sort;
+import org.springframework.data.jpa.domain.JpaSort;
+import org.springframework.data.mapping.PropertyReferenceException;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Stream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class UserRepositoryCommon {
+
+    final String USER_EMAIL = "email@example.com";
+    final String USER_EMAIL2 = "email2@example.com";
+    final String USER_EMAIL3 = "email3@example.com";
+    final String USER_EMAIL4 = "email4@example.com";
+    final Integer INACTIVE_STATUS = 0;
+    final Integer ACTIVE_STATUS = 1;
+    private final String USER_EMAIL5 = "email5@example.com";
+    private final String USER_EMAIL6 = "email6@example.com";
+    private final String USER_NAME_ADAM = "Adam";
+    private final String USER_NAME_PETER = "Peter";
+
+    @Autowired
+    protected UserRepository userRepository;
+
+    @Test
+    @Transactional
+    public void givenUsersWithSameNameInDB_WhenFindAllByName_ThenReturnStreamOfUsers() {
+        User user1 = new User();
+        user1.setName(USER_NAME_ADAM);
+        user1.setEmail(USER_EMAIL);
+        userRepository.save(user1);
+
+        User user2 = new User();
+        user2.setName(USER_NAME_ADAM);
+        user2.setEmail(USER_EMAIL2);
+        userRepository.save(user2);
+
+        User user3 = new User();
+        user3.setName(USER_NAME_ADAM);
+        user3.setEmail(USER_EMAIL3);
+        userRepository.save(user3);
+
+        User user4 = new User();
+        user4.setName("SAMPLE");
+        user4.setEmail(USER_EMAIL4);
+        userRepository.save(user4);
+
+        try (Stream<User> foundUsersStream = userRepository.findAllByName(USER_NAME_ADAM)) {
+            assertThat(foundUsersStream.count()).isEqualTo(3l);
+        }
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindAllWithQueryAnnotation_ThenReturnCollectionWithActiveUsers() {
+        User user1 = new User();
+        user1.setName(USER_NAME_ADAM);
+        user1.setEmail(USER_EMAIL);
+        user1.setStatus(ACTIVE_STATUS);
+        userRepository.save(user1);
+
+        User user2 = new User();
+        user2.setName(USER_NAME_ADAM);
+        user2.setEmail(USER_EMAIL2);
+        user2.setStatus(ACTIVE_STATUS);
+        userRepository.save(user2);
+
+        User user3 = new User();
+        user3.setName(USER_NAME_ADAM);
+        user3.setEmail(USER_EMAIL3);
+        user3.setStatus(INACTIVE_STATUS);
+        userRepository.save(user3);
+
+        Collection<User> allActiveUsers = userRepository.findAllActiveUsers();
+
+        assertThat(allActiveUsers.size()).isEqualTo(2);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindAllWithQueryAnnotationNative_ThenReturnCollectionWithActiveUsers() {
+        User user1 = new User();
+        user1.setName(USER_NAME_ADAM);
+        user1.setEmail(USER_EMAIL);
+        user1.setStatus(ACTIVE_STATUS);
+        userRepository.save(user1);
+
+        User user2 = new User();
+        user2.setName(USER_NAME_ADAM);
+        user2.setEmail(USER_EMAIL2);
+        user2.setStatus(ACTIVE_STATUS);
+        userRepository.save(user2);
+
+        User user3 = new User();
+        user3.setName(USER_NAME_ADAM);
+        user3.setEmail(USER_EMAIL3);
+        user3.setStatus(INACTIVE_STATUS);
+        userRepository.save(user3);
+
+        Collection<User> allActiveUsers = userRepository.findAllActiveUsersNative();
+
+        assertThat(allActiveUsers.size()).isEqualTo(2);
+    }
+
+    @Test
+    public void givenUserInDB_WhenFindUserByStatusWithQueryAnnotation_ThenReturnActiveUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User userByStatus = userRepository.findUserByStatus(ACTIVE_STATUS);
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUserInDB_WhenFindUserByStatusWithQueryAnnotationNative_ThenReturnActiveUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User userByStatus = userRepository.findUserByStatusNative(ACTIVE_STATUS);
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindUserByStatusAndNameWithQueryAnnotationIndexedParams_ThenReturnOneUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User user2 = new User();
+        user2.setName(USER_NAME_PETER);
+        user2.setEmail(USER_EMAIL2);
+        user2.setStatus(ACTIVE_STATUS);
+        userRepository.save(user2);
+
+        User userByStatus = userRepository.findUserByStatusAndName(ACTIVE_STATUS, USER_NAME_ADAM);
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindUserByStatusAndNameWithQueryAnnotationNamedParams_ThenReturnOneUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User user2 = new User();
+        user2.setName(USER_NAME_PETER);
+        user2.setEmail(USER_EMAIL2);
+        user2.setStatus(ACTIVE_STATUS);
+        userRepository.save(user2);
+
+        User userByStatus = userRepository.findUserByStatusAndNameNamedParams(ACTIVE_STATUS, USER_NAME_ADAM);
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindUserByStatusAndNameWithQueryAnnotationNativeNamedParams_ThenReturnOneUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User user2 = new User();
+        user2.setName(USER_NAME_PETER);
+        user2.setEmail(USER_EMAIL2);
+        user2.setStatus(ACTIVE_STATUS);
+        userRepository.save(user2);
+
+        User userByStatus = userRepository.findUserByStatusAndNameNamedParamsNative(ACTIVE_STATUS, USER_NAME_ADAM);
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindUserByStatusAndNameWithQueryAnnotationNamedParamsCustomNames_ThenReturnOneUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User user2 = new User();
+        user2.setName(USER_NAME_PETER);
+        user2.setEmail(USER_EMAIL2);
+        user2.setStatus(ACTIVE_STATUS);
+        userRepository.save(user2);
+
+        User userByStatus = userRepository.findUserByUserStatusAndUserName(ACTIVE_STATUS, USER_NAME_ADAM);
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindUserByNameLikeWithQueryAnnotationIndexedParams_ThenReturnUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User userByStatus = userRepository.findUserByNameLike("Ad");
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindUserByNameLikeWithQueryAnnotationNamedParams_ThenReturnUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User userByStatus = userRepository.findUserByNameLikeNamedParam("Ad");
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindUserByNameLikeWithQueryAnnotationNative_ThenReturnUser() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setEmail(USER_EMAIL);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        User userByStatus = userRepository.findUserByNameLikeNative("Ad");
+
+        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindAllWithSortByName_ThenReturnUsersSorted() {
+        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
+        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
+
+        List<User> usersSortByName = userRepository.findAll(new Sort(Sort.Direction.ASC, "name"));
+
+        assertThat(usersSortByName.get(0)
+          .getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test(expected = PropertyReferenceException.class)
+    public void givenUsersInDB_WhenFindAllSortWithFunction_ThenThrowException() {
+        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
+        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
+
+        userRepository.findAll(new Sort(Sort.Direction.ASC, "name"));
+
+        List<User> usersSortByNameLength = userRepository.findAll(new Sort("LENGTH(name)"));
+
+        assertThat(usersSortByNameLength.get(0)
+          .getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindAllSortWithFunctionQueryAnnotationJPQL_ThenReturnUsersSorted() {
+        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
+        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
+
+        userRepository.findAllUsers(new Sort("name"));
+
+        List<User> usersSortByNameLength = userRepository.findAllUsers(JpaSort.unsafe("LENGTH(name)"));
+
+        assertThat(usersSortByNameLength.get(0)
+          .getName()).isEqualTo(USER_NAME_ADAM);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindAllWithPageRequestQueryAnnotationJPQL_ThenReturnPageOfUsers() {
+        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
+        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE1", USER_EMAIL4, INACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE2", USER_EMAIL5, INACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE3", USER_EMAIL6, INACTIVE_STATUS));
+
+        Page<User> usersPage = userRepository.findAllUsersWithPagination(new PageRequest(1, 3));
+
+        assertThat(usersPage.getContent()
+          .get(0)
+          .getName()).isEqualTo("SAMPLE1");
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindAllWithPageRequestQueryAnnotationNative_ThenReturnPageOfUsers() {
+        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
+        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE1", USER_EMAIL4, INACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE2", USER_EMAIL5, INACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE3", USER_EMAIL6, INACTIVE_STATUS));
+
+        Page<User> usersSortByNameLength = userRepository.findAllUsersWithPaginationNative(new PageRequest(1, 3));
+
+        assertThat(usersSortByNameLength.getContent()
+          .get(0)
+          .getName()).isEqualTo("SAMPLE1");
+    }
+
+    @Test
+    @Transactional
+    public void givenUsersInDB_WhenUpdateStatusForNameModifyingQueryAnnotationJPQL_ThenModifyMatchingUsers() {
+        userRepository.save(new User("SAMPLE", USER_EMAIL, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE1", USER_EMAIL2, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE", USER_EMAIL3, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE3", USER_EMAIL4, ACTIVE_STATUS));
+
+        int updatedUsersSize = userRepository.updateUserSetStatusForName(INACTIVE_STATUS, "SAMPLE");
+
+        assertThat(updatedUsersSize).isEqualTo(2);
+    }
+
+    @Test
+    public void givenUsersInDB_WhenFindByEmailsWithDynamicQuery_ThenReturnCollection() {
+
+        User user1 = new User();
+        user1.setEmail(USER_EMAIL);
+        userRepository.save(user1);
+
+        User user2 = new User();
+        user2.setEmail(USER_EMAIL2);
+        userRepository.save(user2);
+
+        User user3 = new User();
+        user3.setEmail(USER_EMAIL3);
+        userRepository.save(user3);
+
+        Set<String> emails = new HashSet<>();
+        emails.add(USER_EMAIL2);
+        emails.add(USER_EMAIL3);
+
+        Collection<User> usersWithEmails = userRepository.findUserByEmails(emails);
+
+        assertThat(usersWithEmails.size()).isEqualTo(2);
+    }
+
+    @After
+    public void cleanUp() {
+        userRepository.deleteAll();
+    }
+}
diff --git a/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryIntegrationTest.java b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryIntegrationTest.java
index b05086d00e..6bcbb6dcaa 100644
--- a/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryIntegrationTest.java
+++ b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryIntegrationTest.java
@@ -1,28 +1,14 @@
 package com.baeldung.dao.repositories;
 
 import com.baeldung.config.PersistenceConfiguration;
-import com.baeldung.dao.repositories.user.UserRepository;
 import com.baeldung.domain.user.User;
-import org.junit.After;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.data.domain.Page;
-import org.springframework.data.domain.PageRequest;
-import org.springframework.data.domain.Sort;
-import org.springframework.data.jpa.domain.JpaSort;
-import org.springframework.data.mapping.PropertyReferenceException;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.transaction.annotation.Transactional;
 
-import java.util.Collection;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
-import java.util.stream.Stream;
-
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
@@ -31,327 +17,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 @RunWith(SpringRunner.class)
 @SpringBootTest(classes = PersistenceConfiguration.class)
 @DirtiesContext
-public class UserRepositoryIntegrationTest {
-
-    private final String USER_NAME_ADAM = "Adam";
-    private final String USER_NAME_PETER = "Peter";
-
-    private final String USER_EMAIL = "email@example.com";
-    private final String USER_EMAIL2 = "email2@example.com";
-    private final String USER_EMAIL3 = "email3@example.com";
-    private final String USER_EMAIL4 = "email4@example.com";
-    private final String USER_EMAIL5 = "email5@example.com";
-    private final String USER_EMAIL6 = "email6@example.com";
-
-    private final Integer INACTIVE_STATUS = 0;
-    private final Integer ACTIVE_STATUS = 1;
-
-    @Autowired
-    private UserRepository userRepository;
-
-    @Test
-    @Transactional
-    public void givenUsersWithSameNameInDBWhenFindAllByNameThenReturnStreamOfUsers() {
-        User user1 = new User();
-        user1.setName(USER_NAME_ADAM);
-        user1.setEmail(USER_EMAIL);
-        userRepository.save(user1);
-
-        User user2 = new User();
-        user2.setName(USER_NAME_ADAM);
-        user2.setEmail(USER_EMAIL2);
-        userRepository.save(user2);
-
-        User user3 = new User();
-        user3.setName(USER_NAME_ADAM);
-        user3.setEmail(USER_EMAIL3);
-        userRepository.save(user3);
-
-        User user4 = new User();
-        user4.setName("SAMPLE");
-        user4.setEmail(USER_EMAIL4);
-        userRepository.save(user4);
-
-        try (Stream<User> foundUsersStream = userRepository.findAllByName(USER_NAME_ADAM)) {
-            assertThat(foundUsersStream.count()).isEqualTo(3l);
-        }
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindAllWithQueryAnnotationThenReturnCollectionWithActiveUsers() {
-        User user1 = new User();
-        user1.setName(USER_NAME_ADAM);
-        user1.setEmail(USER_EMAIL);
-        user1.setStatus(ACTIVE_STATUS);
-        userRepository.save(user1);
-
-        User user2 = new User();
-        user2.setName(USER_NAME_ADAM);
-        user2.setEmail(USER_EMAIL2);
-        user2.setStatus(ACTIVE_STATUS);
-        userRepository.save(user2);
-
-        User user3 = new User();
-        user3.setName(USER_NAME_ADAM);
-        user3.setEmail(USER_EMAIL3);
-        user3.setStatus(INACTIVE_STATUS);
-        userRepository.save(user3);
-
-        Collection<User> allActiveUsers = userRepository.findAllActiveUsers();
-
-        assertThat(allActiveUsers.size()).isEqualTo(2);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindAllWithQueryAnnotationNativeThenReturnCollectionWithActiveUsers() {
-        User user1 = new User();
-        user1.setName(USER_NAME_ADAM);
-        user1.setEmail(USER_EMAIL);
-        user1.setStatus(ACTIVE_STATUS);
-        userRepository.save(user1);
-
-        User user2 = new User();
-        user2.setName(USER_NAME_ADAM);
-        user2.setEmail(USER_EMAIL2);
-        user2.setStatus(ACTIVE_STATUS);
-        userRepository.save(user2);
-
-        User user3 = new User();
-        user3.setName(USER_NAME_ADAM);
-        user3.setEmail(USER_EMAIL3);
-        user3.setStatus(INACTIVE_STATUS);
-        userRepository.save(user3);
-
-        Collection<User> allActiveUsers = userRepository.findAllActiveUsersNative();
-
-        assertThat(allActiveUsers.size()).isEqualTo(2);
-    }
-
-    @Test
-    public void givenUserInDBWhenFindUserByStatusWithQueryAnnotationThenReturnActiveUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User userByStatus = userRepository.findUserByStatus(ACTIVE_STATUS);
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUserInDBWhenFindUserByStatusWithQueryAnnotationNativeThenReturnActiveUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User userByStatus = userRepository.findUserByStatusNative(ACTIVE_STATUS);
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindUserByStatusAndNameWithQueryAnnotationIndexedParamsThenReturnOneUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User user2 = new User();
-        user2.setName(USER_NAME_PETER);
-        user2.setEmail(USER_EMAIL2);
-        user2.setStatus(ACTIVE_STATUS);
-        userRepository.save(user2);
-
-        User userByStatus = userRepository.findUserByStatusAndName(ACTIVE_STATUS, USER_NAME_ADAM);
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindUserByStatusAndNameWithQueryAnnotationNamedParamsThenReturnOneUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User user2 = new User();
-        user2.setName(USER_NAME_PETER);
-        user2.setEmail(USER_EMAIL2);
-        user2.setStatus(ACTIVE_STATUS);
-        userRepository.save(user2);
-
-        User userByStatus = userRepository.findUserByStatusAndNameNamedParams(ACTIVE_STATUS, USER_NAME_ADAM);
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindUserByStatusAndNameWithQueryAnnotationNativeNamedParamsThenReturnOneUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User user2 = new User();
-        user2.setName(USER_NAME_PETER);
-        user2.setEmail(USER_EMAIL2);
-        user2.setStatus(ACTIVE_STATUS);
-        userRepository.save(user2);
-
-        User userByStatus = userRepository.findUserByStatusAndNameNamedParamsNative(ACTIVE_STATUS, USER_NAME_ADAM);
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindUserByStatusAndNameWithQueryAnnotationNamedParamsCustomNamesThenReturnOneUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User user2 = new User();
-        user2.setName(USER_NAME_PETER);
-        user2.setEmail(USER_EMAIL2);
-        user2.setStatus(ACTIVE_STATUS);
-        userRepository.save(user2);
-
-        User userByStatus = userRepository.findUserByUserStatusAndUserName(ACTIVE_STATUS, USER_NAME_ADAM);
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindUserByNameLikeWithQueryAnnotationIndexedParamsThenReturnUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User userByStatus = userRepository.findUserByNameLike("Ad");
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindUserByNameLikeWithQueryAnnotationNamedParamsThenReturnUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User userByStatus = userRepository.findUserByNameLikeNamedParam("Ad");
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindUserByNameLikeWithQueryAnnotationNativeThenReturnUser() {
-        User user = new User();
-        user.setName(USER_NAME_ADAM);
-        user.setEmail(USER_EMAIL);
-        user.setStatus(ACTIVE_STATUS);
-        userRepository.save(user);
-
-        User userByStatus = userRepository.findUserByNameLikeNative("Ad");
-
-        assertThat(userByStatus.getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindAllWithSortByNameThenReturnUsersSorted() {
-        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
-        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
-
-        List<User> usersSortByName = userRepository.findAll(new Sort(Sort.Direction.ASC, "name"));
-
-        assertThat(usersSortByName.get(0)
-            .getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test(expected = PropertyReferenceException.class)
-    public void givenUsersInDBWhenFindAllSortWithFunctionThenThrowException() {
-        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
-        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
-
-        userRepository.findAll(new Sort(Sort.Direction.ASC, "name"));
-
-        List<User> usersSortByNameLength = userRepository.findAll(new Sort("LENGTH(name)"));
-
-        assertThat(usersSortByNameLength.get(0)
-            .getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindAllSortWithFunctionQueryAnnotationJPQLThenReturnUsersSorted() {
-        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
-        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
-
-        userRepository.findAllUsers(new Sort("name"));
-
-        List<User> usersSortByNameLength = userRepository.findAllUsers(JpaSort.unsafe("LENGTH(name)"));
-
-        assertThat(usersSortByNameLength.get(0)
-            .getName()).isEqualTo(USER_NAME_ADAM);
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindAllWithPageRequestQueryAnnotationJPQLThenReturnPageOfUsers() {
-        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
-        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE1", USER_EMAIL4, INACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE2", USER_EMAIL5, INACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE3", USER_EMAIL6, INACTIVE_STATUS));
-
-        Page<User> usersPage = userRepository.findAllUsersWithPagination(new PageRequest(1, 3));
-
-        assertThat(usersPage.getContent()
-            .get(0)
-            .getName()).isEqualTo("SAMPLE1");
-    }
-
-    @Test
-    public void givenUsersInDBWhenFindAllWithPageRequestQueryAnnotationNativeThenReturnPageOfUsers() {
-        userRepository.save(new User(USER_NAME_ADAM, USER_EMAIL, ACTIVE_STATUS));
-        userRepository.save(new User(USER_NAME_PETER, USER_EMAIL2, ACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE", USER_EMAIL3, INACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE1", USER_EMAIL4, INACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE2", USER_EMAIL5, INACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE3", USER_EMAIL6, INACTIVE_STATUS));
-
-        Page<User> usersSortByNameLength = userRepository.findAllUsersWithPaginationNative(new PageRequest(1, 3));
-
-        assertThat(usersSortByNameLength.getContent()
-            .get(0)
-            .getName()).isEqualTo("SAMPLE1");
-    }
-
-    @Test
-    @Transactional
-    public void givenUsersInDBWhenUpdateStatusForNameModifyingQueryAnnotationJPQLThenModifyMatchingUsers() {
-        userRepository.save(new User("SAMPLE", USER_EMAIL, ACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE1", USER_EMAIL2, ACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE", USER_EMAIL3, ACTIVE_STATUS));
-        userRepository.save(new User("SAMPLE3", USER_EMAIL4, ACTIVE_STATUS));
-
-        int updatedUsersSize = userRepository.updateUserSetStatusForName(INACTIVE_STATUS, "SAMPLE");
-
-        assertThat(updatedUsersSize).isEqualTo(2);
-    }
+public class UserRepositoryIntegrationTest extends UserRepositoryCommon {
 
     @Test
     @Transactional
@@ -366,34 +32,4 @@ public class UserRepositoryIntegrationTest {
 
         assertThat(updatedUsersSize).isEqualTo(2);
     }
-
-    @Test
-    public void givenUsersInDBWhenFindByEmailsWithDynamicQueryThenReturnCollection() {
-
-        User user1 = new User();
-        user1.setEmail(USER_EMAIL);
-        userRepository.save(user1);
-
-        User user2 = new User();
-        user2.setEmail(USER_EMAIL2);
-        userRepository.save(user2);
-
-        User user3 = new User();
-        user3.setEmail(USER_EMAIL3);
-        userRepository.save(user3);
-
-        Set<String> emails = new HashSet<>();
-        emails.add(USER_EMAIL2);
-        emails.add(USER_EMAIL3);
-
-        Collection<User> usersWithEmails = userRepository.findUserByEmails(emails);
-
-        assertThat(usersWithEmails.size()).isEqualTo(2);
-    }
-
-    @After
-    public void cleanUp() {
-        userRepository.deleteAll();
-    }
-
 }
diff --git a/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryTCAutoIntegrationTest.java b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryTCAutoIntegrationTest.java
new file mode 100644
index 0000000000..4b58be487c
--- /dev/null
+++ b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryTCAutoIntegrationTest.java
@@ -0,0 +1,40 @@
+package com.baeldung.dao.repositories;
+
+import com.baeldung.domain.user.User;
+import com.baeldung.util.BaeldungPostgresqlContainer;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.transaction.annotation.Transactional;
+import org.testcontainers.containers.PostgreSQLContainer;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Created by adam.
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest
+@ActiveProfiles({"tc", "tc-auto"})
+public class UserRepositoryTCAutoIntegrationTest extends UserRepositoryCommon {
+
+    @ClassRule
+    public static PostgreSQLContainer postgreSQLContainer = BaeldungPostgresqlContainer.getInstance();
+
+    @Test
+    @Transactional
+    public void givenUsersInDB_WhenUpdateStatusForNameModifyingQueryAnnotationNativePostgres_ThenModifyMatchingUsers() {
+        userRepository.save(new User("SAMPLE", USER_EMAIL, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE1", USER_EMAIL2, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE", USER_EMAIL3, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE3", USER_EMAIL4, ACTIVE_STATUS));
+        userRepository.flush();
+
+        int updatedUsersSize = userRepository.updateUserSetStatusForNameNativePostgres(INACTIVE_STATUS, "SAMPLE");
+
+        assertThat(updatedUsersSize).isEqualTo(2);
+    }
+}
diff --git a/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryTCIntegrationTest.java b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryTCIntegrationTest.java
new file mode 100644
index 0000000000..ccbc3b3fe2
--- /dev/null
+++ b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/dao/repositories/UserRepositoryTCIntegrationTest.java
@@ -0,0 +1,55 @@
+package com.baeldung.dao.repositories;
+
+import com.baeldung.domain.user.User;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.util.TestPropertyValues;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.transaction.annotation.Transactional;
+import org.testcontainers.containers.PostgreSQLContainer;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+@ActiveProfiles("tc")
+@ContextConfiguration(initializers = {UserRepositoryTCIntegrationTest.Initializer.class})
+public class UserRepositoryTCIntegrationTest extends UserRepositoryCommon {
+
+    @ClassRule
+    public static PostgreSQLContainer postgreSQLContainer = new PostgreSQLContainer("postgres:11.1")
+      .withDatabaseName("integration-tests-db")
+      .withUsername("sa")
+      .withPassword("sa");
+
+    @Test
+    @Transactional
+    public void givenUsersInDB_WhenUpdateStatusForNameModifyingQueryAnnotationNative_ThenModifyMatchingUsers() {
+        userRepository.save(new User("SAMPLE", USER_EMAIL, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE1", USER_EMAIL2, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE", USER_EMAIL3, ACTIVE_STATUS));
+        userRepository.save(new User("SAMPLE3", USER_EMAIL4, ACTIVE_STATUS));
+        userRepository.flush();
+
+        int updatedUsersSize = userRepository.updateUserSetStatusForNameNativePostgres(INACTIVE_STATUS, "SAMPLE");
+
+        assertThat(updatedUsersSize).isEqualTo(2);
+    }
+
+    static class Initializer
+      implements ApplicationContextInitializer<ConfigurableApplicationContext> {
+        public void initialize(ConfigurableApplicationContext configurableApplicationContext) {
+            TestPropertyValues.of(
+              "spring.datasource.url=" + postgreSQLContainer.getJdbcUrl(),
+              "spring.datasource.username=" + postgreSQLContainer.getUsername(),
+              "spring.datasource.password=" + postgreSQLContainer.getPassword()
+            ).applyTo(configurableApplicationContext.getEnvironment());
+        }
+    }
+}
diff --git a/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/util/BaeldungPostgresqlContainer.java b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/util/BaeldungPostgresqlContainer.java
new file mode 100644
index 0000000000..e5ad2dd448
--- /dev/null
+++ b/persistence-modules/spring-data-jpa/src/test/java/com/baeldung/util/BaeldungPostgresqlContainer.java
@@ -0,0 +1,35 @@
+package com.baeldung.util;
+
+import org.testcontainers.containers.PostgreSQLContainer;
+
+public class BaeldungPostgresqlContainer extends PostgreSQLContainer<BaeldungPostgresqlContainer> {
+
+    private static final String IMAGE_VERSION = "postgres:11.1";
+
+    private static BaeldungPostgresqlContainer container;
+
+
+    private BaeldungPostgresqlContainer() {
+        super(IMAGE_VERSION);
+    }
+
+    public static BaeldungPostgresqlContainer getInstance() {
+        if (container == null) {
+            container = new BaeldungPostgresqlContainer();
+        }
+        return container;
+    }
+
+    @Override
+    public void start() {
+        super.start();
+        System.setProperty("DB_URL", container.getJdbcUrl());
+        System.setProperty("DB_USERNAME", container.getUsername());
+        System.setProperty("DB_PASSWORD", container.getPassword());
+    }
+
+    @Override
+    public void stop() {
+        //do nothing, JVM handles shut down
+    }
+}
diff --git a/persistence-modules/spring-data-jpa/src/test/resources/application-tc-auto.properties b/persistence-modules/spring-data-jpa/src/test/resources/application-tc-auto.properties
new file mode 100644
index 0000000000..c3005d861f
--- /dev/null
+++ b/persistence-modules/spring-data-jpa/src/test/resources/application-tc-auto.properties
@@ -0,0 +1,4 @@
+# configuration for test containers testing
+spring.datasource.url=${DB_URL}
+spring.datasource.username=${DB_USERNAME}
+spring.datasource.password=${DB_PASSWORD}
diff --git a/persistence-modules/spring-data-jpa/src/test/resources/application-tc.properties b/persistence-modules/spring-data-jpa/src/test/resources/application-tc.properties
new file mode 100644
index 0000000000..3bf8693d53
--- /dev/null
+++ b/persistence-modules/spring-data-jpa/src/test/resources/application-tc.properties
@@ -0,0 +1,4 @@
+# configuration for Test Containers testing
+spring.datasource.driver-class-name=org.postgresql.Driver
+spring.jpa.hibernate.ddl-auto=create-drop
+spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults=false
diff --git a/pom.xml b/pom.xml
index 58d57ade05..1c016a2ea9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -750,6 +750,7 @@
                 <module>spring-security-x509</module>
                 <module>spring-session</module>
                 <module>spring-sleuth</module>
+                <module>spring-soap</module>
                 <module>spring-social-login</module>
                 <module>spring-spel</module>
                 <module>spring-state-machine</module>
@@ -1003,6 +1004,7 @@
                         
                 <module>core-java-concurrency-advanced</module> <!-- very long running? -->
                 <module>core-kotlin</module> <!-- long running? -->
+                <module>core-kotlin-2</module>
 
                 <module>jenkins/hello-world</module>
                 <module>jhipster</module>
@@ -1459,6 +1461,7 @@
                 <module>spring-security-x509</module>
                 <module>spring-session</module>
                 <module>spring-sleuth</module>
+                <module>spring-soap</module>
                 <module>spring-social-login</module>
                 <module>spring-spel</module>
                 <module>spring-state-machine</module>
@@ -1554,6 +1557,7 @@
                 <module>core-java</module>                
                 <module>core-java-concurrency-advanced</module> <!-- very long running? -->
                 <module>core-kotlin</module> <!-- long running? -->
+                <module>core-kotlin-2</module>
 
                 <module>jenkins/hello-world</module>
                 <module>jhipster</module>
diff --git a/spring-boot-libraries/src/main/java/com/baeldung/boot/problem/advice/ExceptionHandler.java b/spring-boot-libraries/src/main/java/com/baeldung/boot/problem/advice/ExceptionHandler.java
index 7b4cbac7f7..18df103733 100644
--- a/spring-boot-libraries/src/main/java/com/baeldung/boot/problem/advice/ExceptionHandler.java
+++ b/spring-boot-libraries/src/main/java/com/baeldung/boot/problem/advice/ExceptionHandler.java
@@ -5,5 +5,12 @@ import org.zalando.problem.spring.web.advice.ProblemHandling;
 
 @ControllerAdvice
 public class ExceptionHandler implements ProblemHandling {
+    
+    // The causal chain of causes is disabled by default, 
+    // but we can easily enable it by overriding the behavior:
+    @Override
+    public boolean isCausalChainsEnabled() {
+        return true;
+    }
 
 }
diff --git a/spring-boot-libraries/src/main/java/com/baeldung/boot/problem/configuration/ProblemDemoConfiguration.java b/spring-boot-libraries/src/main/java/com/baeldung/boot/problem/configuration/ProblemDemoConfiguration.java
index 209ff553c7..f5e6a6b99a 100644
--- a/spring-boot-libraries/src/main/java/com/baeldung/boot/problem/configuration/ProblemDemoConfiguration.java
+++ b/spring-boot-libraries/src/main/java/com/baeldung/boot/problem/configuration/ProblemDemoConfiguration.java
@@ -12,6 +12,8 @@ public class ProblemDemoConfiguration {
 
     @Bean
     public ObjectMapper objectMapper() {
-        return new ObjectMapper().registerModules(new ProblemModule(), new ConstraintViolationProblemModule());
+        // In this example, stack traces support is enabled by default. 
+        // If you want to disable stack traces just use new ProblemModule() instead of new ProblemModule().withStackTraces()
+        return new ObjectMapper().registerModules(new ProblemModule().withStackTraces(), new ConstraintViolationProblemModule());
     }
 }
diff --git a/spring-boot-libraries/src/test/java/com/baeldung/boot/problem/controller/ProblemDemoControllerIntegrationTest.java b/spring-boot-libraries/src/test/java/com/baeldung/boot/problem/controller/ProblemDemoControllerIntegrationTest.java
index 3b7e43a565..5ced1034c4 100644
--- a/spring-boot-libraries/src/test/java/com/baeldung/boot/problem/controller/ProblemDemoControllerIntegrationTest.java
+++ b/spring-boot-libraries/src/test/java/com/baeldung/boot/problem/controller/ProblemDemoControllerIntegrationTest.java
@@ -1,6 +1,8 @@
 package com.baeldung.boot.problem.controller;
 
+import static org.hamcrest.CoreMatchers.containsString;
 import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.notNullValue;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.delete;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.put;
@@ -71,5 +73,29 @@ public class ProblemDemoControllerIntegrationTest {
             .andExpect(jsonPath("$.detail", equalTo("You can't delete this task")))
             .andExpect(status().isForbidden());
     }
+    
+    @Test
+    public void whenMakeGetCallWithInvalidIdFormat_thenReturnBadRequestResponseWithStackTrace() throws Exception {
+        mockMvc.perform(get("/tasks/invalid-id").contentType(MediaType.APPLICATION_PROBLEM_JSON_VALUE))
+            .andDo(print())
+            .andExpect(jsonPath("$.title", equalTo("Bad Request")))
+            .andExpect(jsonPath("$.status", equalTo(400)))
+            .andExpect(jsonPath("$.stacktrace", notNullValue()))
+            .andExpect(status().isBadRequest());
+    }
+    
+    @Test
+    public void whenMakeGetCallWithInvalidIdFormat_thenReturnBadRequestResponseWithCause() throws Exception {
+        mockMvc.perform(get("/tasks/invalid-id").contentType(MediaType.APPLICATION_PROBLEM_JSON_VALUE))
+            .andDo(print())
+            .andExpect(jsonPath("$.title", equalTo("Bad Request")))
+            .andExpect(jsonPath("$.status", equalTo(400)))
+            .andExpect(jsonPath("$.cause", notNullValue()))
+            .andExpect(jsonPath("$.cause.title", equalTo("Internal Server Error")))
+            .andExpect(jsonPath("$.cause.status", equalTo(500)))
+            .andExpect(jsonPath("$.cause.detail", containsString("For input string:")))
+            .andExpect(jsonPath("$.cause.stacktrace", notNullValue()))
+            .andExpect(status().isBadRequest());
+    }
 
 }
diff --git a/spring-soap/.gitignore b/spring-soap/.gitignore
new file mode 100644
index 0000000000..b83d22266a
--- /dev/null
+++ b/spring-soap/.gitignore
@@ -0,0 +1 @@
+/target/
diff --git a/spring-soap/pom.xml b/spring-soap/pom.xml
new file mode 100644
index 0000000000..2865a4c3bc
--- /dev/null
+++ b/spring-soap/pom.xml
@@ -0,0 +1,68 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.baeldung</groupId>
+    <artifactId>spring-soap</artifactId>
+    <version>1.0.0</version>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.1.2.RELEASE</version>
+    </parent>
+
+    <properties>
+        <java.version>1.8</java.version>
+    </properties>
+
+    <dependencies>
+        <!-- tag::springws[] -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web-services</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>wsdl4j</groupId>
+            <artifactId>wsdl4j</artifactId>
+        </dependency>
+        <!-- end::springws[] -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+
+            <!-- tag::xsd[] -->
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>jaxb2-maven-plugin</artifactId>
+                <version>1.6</version>
+                <executions>
+                    <execution>
+                        <id>xjc</id>
+                        <goals>
+                            <goal>xjc</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                    <schemaDirectory>${project.basedir}/src/main/resources/</schemaDirectory>
+                    <outputDirectory>${project.basedir}/src/main/java</outputDirectory>
+                    <clearOutputDir>false</clearOutputDir>
+                </configuration>
+            </plugin>
+            <!-- end::xsd[] -->
+        </plugins>
+    </build>
+
+</project>
diff --git a/spring-soap/src/main/java/com/baeldung/springsoap/Application.java b/spring-soap/src/main/java/com/baeldung/springsoap/Application.java
new file mode 100644
index 0000000000..ad9258447c
--- /dev/null
+++ b/spring-soap/src/main/java/com/baeldung/springsoap/Application.java
@@ -0,0 +1,12 @@
+package com.baeldung.springsoap;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+}
diff --git a/spring-soap/src/main/java/com/baeldung/springsoap/CountryEndpoint.java b/spring-soap/src/main/java/com/baeldung/springsoap/CountryEndpoint.java
new file mode 100644
index 0000000000..745131767a
--- /dev/null
+++ b/spring-soap/src/main/java/com/baeldung/springsoap/CountryEndpoint.java
@@ -0,0 +1,30 @@
+package com.baeldung.springsoap;
+
+import com.baeldung.springsoap.gen.*;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.ws.server.endpoint.annotation.Endpoint;
+import org.springframework.ws.server.endpoint.annotation.PayloadRoot;
+import org.springframework.ws.server.endpoint.annotation.RequestPayload;
+import org.springframework.ws.server.endpoint.annotation.ResponsePayload;
+
+@Endpoint
+public class CountryEndpoint {
+
+    private static final String NAMESPACE_URI = "http://www.baeldung.com/springsoap/gen";
+
+    private CountryRepository countryRepository;
+
+    @Autowired
+    public CountryEndpoint(CountryRepository countryRepository) {
+        this.countryRepository = countryRepository;
+    }
+
+    @PayloadRoot(namespace = NAMESPACE_URI, localPart = "getCountryRequest")
+    @ResponsePayload
+    public GetCountryResponse getCountry(@RequestPayload GetCountryRequest request) {
+        GetCountryResponse response = new GetCountryResponse();
+        response.setCountry(countryRepository.findCountry(request.getName()));
+
+        return response;
+    }
+}
diff --git a/spring-soap/src/main/java/com/baeldung/springsoap/CountryRepository.java b/spring-soap/src/main/java/com/baeldung/springsoap/CountryRepository.java
new file mode 100644
index 0000000000..8a0f58a64e
--- /dev/null
+++ b/spring-soap/src/main/java/com/baeldung/springsoap/CountryRepository.java
@@ -0,0 +1,47 @@
+package com.baeldung.springsoap;
+
+import com.baeldung.springsoap.gen.*;
+import org.springframework.stereotype.Component;
+import org.springframework.util.Assert;
+
+import javax.annotation.PostConstruct;
+import java.util.HashMap;
+import java.util.Map;
+
+@Component
+public class CountryRepository {
+
+    private static final Map<String, Country> countries = new HashMap<>();
+
+    @PostConstruct
+    public void initData() {
+        Country spain = new Country();
+        spain.setName("Spain");
+        spain.setCapital("Madrid");
+        spain.setCurrency(Currency.EUR);
+        spain.setPopulation(46704314);
+
+        countries.put(spain.getName(), spain);
+
+        Country poland = new Country();
+        poland.setName("Poland");
+        poland.setCapital("Warsaw");
+        poland.setCurrency(Currency.PLN);
+        poland.setPopulation(38186860);
+
+        countries.put(poland.getName(), poland);
+
+        Country uk = new Country();
+        uk.setName("United Kingdom");
+        uk.setCapital("London");
+        uk.setCurrency(Currency.GBP);
+        uk.setPopulation(63705000);
+
+        countries.put(uk.getName(), uk);
+    }
+
+    public Country findCountry(String name) {
+        Assert.notNull(name, "The country's name must not be null");
+        return countries.get(name);
+    }
+}
diff --git a/spring-soap/src/main/java/com/baeldung/springsoap/WebServiceConfig.java b/spring-soap/src/main/java/com/baeldung/springsoap/WebServiceConfig.java
new file mode 100644
index 0000000000..930a961208
--- /dev/null
+++ b/spring-soap/src/main/java/com/baeldung/springsoap/WebServiceConfig.java
@@ -0,0 +1,41 @@
+package com.baeldung.springsoap;
+
+import org.springframework.boot.web.servlet.ServletRegistrationBean;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.ws.config.annotation.EnableWs;
+import org.springframework.ws.config.annotation.WsConfigurerAdapter;
+import org.springframework.ws.transport.http.MessageDispatcherServlet;
+import org.springframework.ws.wsdl.wsdl11.DefaultWsdl11Definition;
+import org.springframework.xml.xsd.SimpleXsdSchema;
+import org.springframework.xml.xsd.XsdSchema;
+
+@EnableWs
+@Configuration
+public class WebServiceConfig extends WsConfigurerAdapter {
+
+    @Bean
+    public ServletRegistrationBean messageDispatcherServlet(ApplicationContext applicationContext) {
+        MessageDispatcherServlet servlet = new MessageDispatcherServlet();
+        servlet.setApplicationContext(applicationContext);
+        servlet.setTransformWsdlLocations(true);
+        return new ServletRegistrationBean(servlet, "/ws/*");
+    }
+
+    @Bean(name = "countries")
+    public DefaultWsdl11Definition defaultWsdl11Definition(XsdSchema countriesSchema) {
+        DefaultWsdl11Definition wsdl11Definition = new DefaultWsdl11Definition();
+        wsdl11Definition.setPortTypeName("CountriesPort");
+        wsdl11Definition.setLocationUri("/ws");
+        wsdl11Definition.setTargetNamespace("http://www.baeldung.com/springsoap/gen");
+        wsdl11Definition.setSchema(countriesSchema);
+        return wsdl11Definition;
+    }
+
+    @Bean
+    public XsdSchema countriesSchema() {
+        return new SimpleXsdSchema(new ClassPathResource("countries.xsd"));
+    }
+}
diff --git a/spring-soap/src/main/resources/countries.xsd b/spring-soap/src/main/resources/countries.xsd
new file mode 100644
index 0000000000..524e5ac2d5
--- /dev/null
+++ b/spring-soap/src/main/resources/countries.xsd
@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:tns="http://www.baeldung.com/springsoap/gen"
+           targetNamespace="http://www.baeldung.com/springsoap/gen" elementFormDefault="qualified">
+
+    <xs:element name="getCountryRequest">
+        <xs:complexType>
+            <xs:sequence>
+                <xs:element name="name" type="xs:string"/>
+            </xs:sequence>
+        </xs:complexType>
+    </xs:element>
+
+    <xs:element name="getCountryResponse">
+        <xs:complexType>
+            <xs:sequence>
+                <xs:element name="country" type="tns:country"/>
+            </xs:sequence>
+        </xs:complexType>
+    </xs:element>
+
+    <xs:complexType name="country">
+        <xs:sequence>
+            <xs:element name="name" type="xs:string"/>
+            <xs:element name="population" type="xs:int"/>
+            <xs:element name="capital" type="xs:string"/>
+            <xs:element name="currency" type="tns:currency"/>
+        </xs:sequence>
+    </xs:complexType>
+
+    <xs:simpleType name="currency">
+        <xs:restriction base="xs:string">
+            <xs:enumeration value="GBP"/>
+            <xs:enumeration value="EUR"/>
+            <xs:enumeration value="PLN"/>
+        </xs:restriction>
+    </xs:simpleType>
+</xs:schema>
\ No newline at end of file
diff --git a/spring-soap/src/test/java/com/baeldung/springsoap/ApplicationIntegrationTest.java b/spring-soap/src/test/java/com/baeldung/springsoap/ApplicationIntegrationTest.java
new file mode 100644
index 0000000000..3b071c286f
--- /dev/null
+++ b/spring-soap/src/test/java/com/baeldung/springsoap/ApplicationIntegrationTest.java
@@ -0,0 +1,39 @@
+package com.baeldung.springsoap;
+
+import com.baeldung.springsoap.gen.GetCountryRequest;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.boot.web.server.LocalServerPort;
+import org.springframework.oxm.jaxb.Jaxb2Marshaller;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.util.ClassUtils;
+import org.springframework.ws.client.core.WebServiceTemplate;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+public class ApplicationIntegrationTest {
+
+    private Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
+
+    @LocalServerPort private int port = 0;
+
+    @Before
+    public void init() throws Exception {
+        marshaller.setPackagesToScan(ClassUtils.getPackageName(GetCountryRequest.class));
+        marshaller.afterPropertiesSet();
+    }
+
+    @Test
+    public void whenSendRequest_thenResponseIsNotNull() {
+        WebServiceTemplate ws = new WebServiceTemplate(marshaller);
+        GetCountryRequest request = new GetCountryRequest();
+        request.setName("Spain");
+
+        assertThat(ws.marshalSendAndReceive("http://localhost:" + port + "/ws", request)).isNotNull();
+    }
+}
diff --git a/spring-soap/src/test/resources/request.xml b/spring-soap/src/test/resources/request.xml
new file mode 100644
index 0000000000..7a94aeeee6
--- /dev/null
+++ b/spring-soap/src/test/resources/request.xml
@@ -0,0 +1,23 @@
+<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
+                  xmlns:gs="http://www.baeldung.com/springsoap/gen">
+    <soapenv:Header/>
+    <soapenv:Body>
+        <gs:getCountryRequest>
+            <gs:name>Spain</gs:name>
+        </gs:getCountryRequest>
+    </soapenv:Body>
+</soapenv:Envelope>
+
+<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
+<SOAP-ENV:Header/>
+<SOAP-ENV:Body>
+    <ns2:getCountryResponse xmlns:ns2="http://www.baeldung.com/springsoap/gen">
+        <ns2:country>
+            <ns2:name>Spain</ns2:name>
+            <ns2:population>46704314</ns2:population>
+            <ns2:capital>Madrid</ns2:capital>
+            <ns2:currency>EUR</ns2:currency>
+        </ns2:country>
+    </ns2:getCountryResponse>
+</SOAP-ENV:Body>
+</SOAP-ENV:Envelope>
\ No newline at end of file