Merge pull request #1 from eugenp/master

update

core-java-modules/core-java-10/README.md

@@ -5,7 +5,7 @@ This module contains articles about Java 10 core features
 ### Relevant Articles: 
 
 - [Java 10 LocalVariable Type-Inference](http://www.baeldung.com/java-10-local-variable-type-inference)
-- [Guide to Java 10](http://www.baeldung.com/java-10-overview)
+- [New Features in Java 10](https://www.baeldung.com/java-10-overview)
 - [Copy a List to Another List in Java](http://www.baeldung.com/java-copy-list-to-another)
 - [Deep Dive Into the New Java JIT Compiler – Graal](https://www.baeldung.com/graal-java-jit-compiler)
 - [Copying Sets in Java](https://www.baeldung.com/java-copy-sets)

core-java-modules/core-java-12/README.md

@@ -1,5 +1,4 @@
 ## Relevant Articles:
 
-
 - [String API Updates in Java 12](https://www.baeldung.com/java12-string-api)
-- [Java 12 New Features](https://www.baeldung.com/java-12-new-features)
+- [New Features in Java 12](https://www.baeldung.com/java-12-new-features)

core-java-modules/core-java-13/README.md

@@ -1,4 +1,4 @@
 ### Relevant articles:
 
 - [Java Switch Statement](https://www.baeldung.com/java-switch)
-- [New Java 13 Features](https://www.baeldung.com/java-13-new-features)
+- [New Features in Java 13](https://www.baeldung.com/java-13-new-features)

core-java-modules/core-java-14/README.md

@@ -10,4 +10,4 @@ This module contains articles about Java 14.
 - [Helpful NullPointerExceptions in Java 14](https://www.baeldung.com/java-14-nullpointerexception)
 - [Foreign Memory Access API in Java 14](https://www.baeldung.com/java-foreign-memory-access)
 - [Java 14 Record Keyword](https://www.baeldung.com/java-record-keyword)
-- [Java 14 – New Features](https://www.baeldung.com/java-14-new-features)
+- [New Features in Java 14](https://www.baeldung.com/java-14-new-features)

core-java-modules/core-java-9-new-features/README.md

@@ -4,7 +4,7 @@ This module contains articles about core Java features that have been introduced
 
 ### Relevant Articles:
 
-- [Java 9 New Features](https://www.baeldung.com/new-java-9)
+- [New Features in Java 9](https://www.baeldung.com/new-java-9)
 - [Java 9 Variable Handles Demystified](http://www.baeldung.com/java-variable-handles)
 - [Exploring the New HTTP Client in Java 9 and 11](http://www.baeldung.com/java-9-http-client)
 - [Multi-Release Jar Files](https://www.baeldung.com/java-multi-release-jar)

core-java-modules/core-java-annotations/src/main/java/com/baeldung/annotations/AnnotatedClass.java

@@ -0,0 +1,8 @@
+package com.baeldung.annotations;
+
+import javax.annotation.Generated;
+
+@RetentionAnnotation
+@Generated("Available only on source code")
+public class AnnotatedClass {
+}

core-java-modules/core-java-annotations/src/main/java/com/baeldung/annotations/RetentionAnnotation.java

@@ -0,0 +1,12 @@
+package com.baeldung.annotations;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import static java.lang.annotation.ElementType.TYPE;
+
+@Target(TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface RetentionAnnotation {
+}

core-java-modules/core-java-annotations/src/test/java/com/baeldung/annotations/AnnotatedClassUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.annotations;
+
+import org.junit.Test;
+
+import java.lang.annotation.Annotation;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+public class AnnotatedClassUnitTest {
+
+    @Test
+    public void whenAnnotationRetentionPolicyRuntime_shouldAccess() {
+        AnnotatedClass anAnnotatedClass = new AnnotatedClass();
+        Annotation[] annotations = anAnnotatedClass.getClass().getAnnotations();
+        assertThat(annotations.length, is(1));
+    }
+}

core-java-modules/core-java-char/README.md

@@ -3,4 +3,4 @@
 This module contains articles about Java Character Class
 
 ### Relevant Articles: 
-- [Character#isAlphabetic vs Character#isLetter](https://www.baeldung.com/java-character-isletter-isalphabetic)
+- [Character#isAlphabetic vs. Character#isLetter](https://www.baeldung.com/java-character-isletter-isalphabetic)

core-java-modules/core-java-collections-4/pom.xml

@@ -25,7 +25,7 @@
     </dependencies>
 
     <properties>
-        <assertj.version>3.18.0</assertj.version>
+        <assertj.version>3.19.0</assertj.version>
     </properties>
 
 </project>

core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/dequestack/ArrayLifoStack.java

@@ -0,0 +1,91 @@
+package com.baeldung.collections.dequestack;
+
+import java.util.ArrayDeque;
+import java.util.Collection;
+import java.util.Deque;
+import java.util.Iterator;
+
+public class ArrayLifoStack<E> implements LifoStack<E> {
+    private final Deque<E> deque = new ArrayDeque<>();
+
+    @Override
+    public void push(E item) {
+        deque.addFirst(item);
+    }
+
+    @Override
+    public E pop() {
+        return deque.removeFirst();
+    }
+
+    @Override
+    public E peek() {
+        return deque.peekFirst();
+    }
+
+    // implementing methods from the Collection interface
+    @Override
+    public int size() {
+        return deque.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return deque.isEmpty();
+    }
+
+    @Override
+    public boolean contains(Object o) {
+        return deque.contains(o);
+    }
+
+    @Override
+    public Iterator<E> iterator() {
+        return deque.iterator();
+    }
+
+    @Override
+    public Object[] toArray() {
+        return deque.toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] a) {
+        return deque.toArray(a);
+    }
+
+    @Override
+    public boolean add(E e) {
+        return deque.add(e);
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        return deque.remove(o);
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> c) {
+        return deque.containsAll(c);
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends E> c) {
+        return deque.addAll(c);
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> c) {
+        return deque.removeAll(c);
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> c) {
+        return deque.retainAll(c);
+    }
+
+    @Override
+    public void clear() {
+        deque.clear();
+    }
+}

core-java-modules/core-java-collections-4/src/main/java/com/baeldung/collections/dequestack/LifoStack.java

@@ -0,0 +1,12 @@
+package com.baeldung.collections.dequestack;
+
+import java.util.Collection;
+
+public interface LifoStack<E> extends Collection<E> {
+
+    E peek();
+
+    E pop();
+
+    void push(E item);
+}

core-java-modules/core-java-collections-4/src/test/java/com/baeldung/collections/dequestack/StackVsDequeUnitTest.java

@@ -0,0 +1,90 @@
+package com.baeldung.collections.dequestack;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.Iterator;
+import java.util.Stack;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class StackVsDequeUnitTest {
+
+    @Test
+    void givenAStack_whenAccessByIndex_thenElementCanBeRead() {
+        Stack<String> myStack = new Stack<>();
+        myStack.push("I am the 1st element."); //index 0
+        myStack.push("I am the 2nd element."); //index 1
+        myStack.push("I am the 3rd element."); //index 2
+        //access by index
+        assertThat(myStack.get(0)).isEqualTo("I am the 1st element.");
+    }
+
+    @Test
+    void givenAStack_whenIterate_thenFromBottomToTop() {
+        Stack<String> myStack = new Stack<>();
+        myStack.push("I am at the bottom.");
+        myStack.push("I am in the middle.");
+        myStack.push("I am at the top.");
+
+        Iterator<String> it = myStack.iterator();
+
+        assertThat(it).toIterable().containsExactly(
+          "I am at the bottom.",
+          "I am in the middle.",
+          "I am at the top.");
+    }
+
+    @Test
+    void givenAStack_whenAddOrRemoveByIndex_thenElementCanBeAddedOrRemoved() {
+        Stack<String> myStack = new Stack<>();
+        myStack.push("I am the 1st element.");
+        myStack.push("I am the 3rd element.");
+
+        assertThat(myStack.size()).isEqualTo(2);
+
+        //insert by index
+        myStack.add(1, "I am the 2nd element.");
+        assertThat(myStack.size()).isEqualTo(3);
+        assertThat(myStack.get(1)).isEqualTo("I am the 2nd element.");
+        //remove by index
+        myStack.remove(1);
+        assertThat(myStack.size()).isEqualTo(2);
+    }
+
+    @Test
+    void givenADeque_whenAddOrRemoveLastElement_thenTheLastElementCanBeAddedOrRemoved() {
+        Deque<String> myStack = new ArrayDeque<>();
+        myStack.push("I am the 1st element.");
+        myStack.push("I am the 2nd element.");
+        myStack.push("I am the 3rd element.");
+
+        assertThat(myStack.size()).isEqualTo(3);
+
+        //insert element to the bottom of the stack
+        myStack.addLast("I am the NEW element.");
+        assertThat(myStack.size()).isEqualTo(4);
+        assertThat(myStack.peek()).isEqualTo("I am the 3rd element.");
+
+        //remove element from the bottom of the stack
+        String removedStr = myStack.removeLast();
+        assertThat(myStack.size()).isEqualTo(3);
+        assertThat(removedStr).isEqualTo("I am the NEW element.");
+    }
+
+    @Test
+    void givenADeque_whenIterate_thenFromTopToBottom() {
+        Deque<String> myStack = new ArrayDeque<>();
+        myStack.push("I am at the bottom.");
+        myStack.push("I am in the middle.");
+        myStack.push("I am at the top.");
+
+        Iterator<String> it = myStack.iterator();
+
+        assertThat(it).toIterable().containsExactly(
+          "I am at the top.",
+          "I am in the middle.",
+          "I am at the bottom.");
+    }
+}

core-java-modules/core-java-collections-maps-3/README.md

@@ -7,4 +7,5 @@ This module contains articles about Map data structures in Java.
 - [Comparing Two HashMaps in Java](https://www.baeldung.com/java-compare-hashmaps)
 - [The Map.computeIfAbsent() Method](https://www.baeldung.com/java-map-computeifabsent)
 - [Collections.synchronizedMap vs. ConcurrentHashMap](https://www.baeldung.com/java-synchronizedmap-vs-concurrenthashmap)
+- [Java HashMap Load Factor](https://www.baeldung.com/java-hashmap-load-factor)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-maps-2)

core-java-modules/core-java-collections-maps-3/pom.xml

@@ -20,6 +20,11 @@
             <artifactId>jmh-core</artifactId>
             <version>${jmh-core.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
     </dependencies>
 
     <properties>

core-java-modules/core-java-collections-maps-3/src/main/java/com/baeldung/map/propertieshashmap/PropertiesToHashMapConverter.java

@@ -0,0 +1,39 @@
+package com.baeldung.map.propertieshashmap;
+
+import com.google.common.collect.Maps;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+import java.util.stream.Collectors;
+
+public class PropertiesToHashMapConverter {
+
+    @SuppressWarnings({"rawtypes", "unchecked"})
+    public static HashMap<String, String> typeCastConvert(Properties prop) {
+        Map step1 = prop;
+        Map<String, String> step2 = (Map<String, String>) step1;
+        return new HashMap<>(step2);
+    }
+
+    public static HashMap<String, String> loopConvert(Properties prop) {
+        HashMap<String, String> retMap = new HashMap<>();
+        for (Map.Entry<Object, Object> entry : prop.entrySet()) {
+            retMap.put(String.valueOf(entry.getKey()), String.valueOf(entry.getValue()));
+        }
+        return retMap;
+    }
+
+    public static HashMap<String, String> streamConvert(Properties prop) {
+        return prop.entrySet().stream().collect(
+                Collectors.toMap(
+                  e -> String.valueOf(e.getKey()),
+                  e -> String.valueOf(e.getValue()),
+                  (prev, next) -> next, HashMap::new
+                ));
+    }
+
+    public static HashMap<String, String> guavaConvert(Properties prop) {
+        return Maps.newHashMap(Maps.fromProperties(prop));
+    }
+}

core-java-modules/core-java-collections-maps-3/src/test/java/com/baeldung/map/propertieshashmap/PropertiesToHashMapConverterUnitTest.java

@@ -0,0 +1,192 @@
+package com.baeldung.map.propertieshashmap;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.HashMap;
+import java.util.Properties;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class PropertiesToHashMapConverterUnitTest {
+
+    private Properties properties;
+
+    private final static String propertyFileName = "toHashMap.properties";
+
+    @BeforeEach
+    public void setup() throws IOException {
+        properties = new Properties();
+        try (InputStream is = getClass().getClassLoader().getResourceAsStream(propertyFileName)) {
+            if (is != null) {
+                properties.load(is);
+            }
+        }
+    }
+
+    @Test
+    public void havingPropertiesLoaded_whenCheck_thenEquals() {
+        assertEquals(3, properties.size());
+        assertEquals("str_value", properties.get("property1"));
+        assertEquals("123", properties.get("property2"));
+        assertEquals("", properties.get("property3"));
+    }
+
+    @Test
+    public void whenPropertiesModified_thenTypeSafeIssues() {
+        compromiseProperties(properties);
+
+        assertEquals(5, properties.size());
+
+        assertNull(properties.getProperty("property4"));
+        assertNotEquals(String.class, properties.get("property4").getClass());
+        assertEquals(456, properties.get("property4"));
+
+
+        assertNull(properties.getProperty("5"));
+        assertNotEquals(String.class, properties.get(5).getClass());
+        assertEquals(10.11, properties.get(5));
+    }
+
+    @Test
+    public void havingNonModifiedProperties_whenTypeCastConvert_thenNoTypeSafeIssues() {
+        HashMap<String, String> hMap = PropertiesToHashMapConverter.typeCastConvert(properties);
+
+        assertEquals(3, hMap.size());
+        assertEquals(String.class, hMap.get("property1").getClass());
+        assertEquals(properties.get("property1"), hMap.get("property1"));
+        assertEquals(String.class, hMap.get("property2").getClass());
+        assertEquals(properties.get("property2"), hMap.get("property2"));
+        assertEquals(String.class, hMap.get("property3").getClass());
+        assertEquals(properties.get("property3"), hMap.get("property3"));
+    }
+
+    @Test
+    public void havingModifiedProperties_whenTypeCastConvert_thenClassCastException() {
+        compromiseProperties(properties);
+        HashMap<String, String> hMap = PropertiesToHashMapConverter.typeCastConvert(properties);
+        assertEquals(5, hMap.size());
+
+        assertThrows(ClassCastException.class, () -> {
+            String s = hMap.get("property4");
+        });
+        assertEquals(Integer.class, ((Object) hMap.get("property4")).getClass());
+
+        assertNull(hMap.get("5"));
+        assertNotNull(hMap.get(5));
+        assertThrows(ClassCastException.class, () -> {
+            String s = hMap.get(5);
+        });
+        assertEquals(Double.class, ((Object) hMap.get(5)).getClass());
+    }
+
+    @Test
+    public void havingNonModifiedProperties_whenLoopConvert_thenNoTypeSafeIssues() {
+        HashMap<String, String> hMap = PropertiesToHashMapConverter.loopConvert(properties);
+
+        assertEquals(3, hMap.size());
+        assertEquals(String.class, hMap.get("property1").getClass());
+        assertEquals(properties.get("property1"), hMap.get("property1"));
+        assertEquals(String.class, hMap.get("property2").getClass());
+        assertEquals(properties.get("property2"), hMap.get("property2"));
+        assertEquals(String.class, hMap.get("property3").getClass());
+        assertEquals(properties.get("property3"), hMap.get("property3"));
+    }
+
+    @Test
+    public void havingModifiedProperties_whenLoopConvert_thenNoClassCastException() {
+        compromiseProperties(properties);
+        HashMap<String, String> hMap = PropertiesToHashMapConverter.loopConvert(properties);
+        assertEquals(5, hMap.size());
+
+        assertDoesNotThrow(() -> {
+            String s = hMap.get("property4");
+        });
+        assertEquals(String.class, hMap.get("property4").getClass());
+        assertEquals("456", hMap.get("property4"));
+
+        assertDoesNotThrow(() -> {
+            String s = hMap.get("5");
+        });
+        assertEquals("10.11", hMap.get("5"));
+    }
+
+    @Test
+    public void havingNonModifiedProperties_whenStreamConvert_thenNoTypeSafeIssues() {
+        HashMap<String, String> hMap = PropertiesToHashMapConverter.streamConvert(properties);
+
+        assertEquals(3, hMap.size());
+        assertEquals(String.class, hMap.get("property1").getClass());
+        assertEquals(properties.get("property1"), hMap.get("property1"));
+        assertEquals(String.class, hMap.get("property2").getClass());
+        assertEquals(properties.get("property2"), hMap.get("property2"));
+        assertEquals(String.class, hMap.get("property3").getClass());
+        assertEquals(properties.get("property3"), hMap.get("property3"));
+    }
+
+    @Test
+    public void havingModifiedProperties_whenStreamConvert_thenNoClassCastException() {
+        compromiseProperties(properties);
+        HashMap<String, String> hMap = PropertiesToHashMapConverter.streamConvert(properties);
+        assertEquals(5, hMap.size());
+
+        assertDoesNotThrow(() -> {
+            String s = hMap.get("property4");
+        });
+        assertEquals(String.class, hMap.get("property4").getClass());
+        assertEquals("456", hMap.get("property4"));
+
+        assertDoesNotThrow(() -> {
+            String s = hMap.get("5");
+        });
+        assertEquals("10.11", hMap.get("5"));
+    }
+
+    @Test
+    public void havingModifiedProperties_whenLoopConvertAndStreamConvert_thenHashMapsSame() {
+        compromiseProperties(properties);
+        HashMap<String, String> hMap1 = PropertiesToHashMapConverter.loopConvert(properties);
+        HashMap<String, String> hMap2 = PropertiesToHashMapConverter.streamConvert(properties);
+
+        assertEquals(hMap2, hMap1);
+    }
+
+    @Test
+    public void havingNonModifiedProperties_whenGuavaConvert_thenNoTypeSafeIssues() {
+        HashMap<String, String> hMap = PropertiesToHashMapConverter.guavaConvert(properties);
+
+        assertEquals(3, hMap.size());
+        assertEquals(String.class, hMap.get("property1").getClass());
+        assertEquals(properties.get("property1"), hMap.get("property1"));
+        assertEquals(String.class, hMap.get("property2").getClass());
+        assertEquals(properties.get("property2"), hMap.get("property2"));
+        assertEquals(String.class, hMap.get("property3").getClass());
+        assertEquals(properties.get("property3"), hMap.get("property3"));
+    }
+
+    @Test
+    public void havingModifiedProperties_whenGuavaConvert_thenUnableToConvertAndThrowException() {
+        compromiseProperties(properties);
+        assertThrows(Exception.class, () -> PropertiesToHashMapConverter.guavaConvert(properties));
+    }
+
+    @Test
+    public void havingModifiedPropertiesWithNoIntegerValue_whenGuavaConvert_thenNullPointerException() {
+        properties.put("property4", 456);
+        assertThrows(NullPointerException.class, () -> PropertiesToHashMapConverter.guavaConvert(properties));
+    }
+
+    @Test
+    public void havingModifiedPropertiesWithNoIntegerKey_whenGuavaConvert_thenClassCastException() {
+        properties.put(5, 10.11);
+        assertThrows(ClassCastException.class, () -> PropertiesToHashMapConverter.guavaConvert(properties));
+    }
+
+
+    private void compromiseProperties(Properties prop) {
+        prop.put("property4", 456);
+        prop.put(5, 10.11);
+    }
+}

core-java-modules/core-java-collections-maps-3/src/test/resources/toHashMap.properties

@@ -0,0 +1,3 @@
+property1=str_value
+property2=123
+property3=

core-java-modules/core-java-jpms/decoupling-pattern2/consumermodule/pom.xml

@@ -17,7 +17,7 @@
     <dependencies>
         <dependency>
             <groupId>com.baeldung.servicemodule</groupId>
-            <artifactId>servicemodule</artifactId>
+            <artifactId>servicemodule2</artifactId>
             <version>${servicemodule.version}</version>
         </dependency>
         <dependency>
@@ -41,4 +41,4 @@
         <providermodule.version>1.0</providermodule.version>
     </properties>
 
-</project>
+</project>

core-java-modules/core-java-lang-3/README.md

@@ -11,4 +11,5 @@ This module contains articles about core features in the Java language
 - [The transient Keyword in Java](https://www.baeldung.com/java-transient-keyword)
 - [How to Access an Iteration Counter in a For Each Loop](https://www.baeldung.com/java-foreach-counter)
 - [Comparing Doubles in Java](https://www.baeldung.com/java-comparing-doubles)
+- [Guide to Implementing the compareTo Method](https://www.baeldung.com/java-compareto)
 - [[<-- Prev]](/core-java-modules/core-java-lang-2)

core-java-modules/core-java-lang-math-3/README.md

@@ -4,6 +4,5 @@
 
 ### Relevant articles:
 
-- [Calculate Factorial in Java](https://www.baeldung.com/java-calculate-factorial)
 - [Evaluating a Math Expression in Java](https://www.baeldung.com/java-evaluate-math-expression-string)
 - More articles: [[<-- Prev]](/core-java-modules/core-java-lang-math-2)

core-java-modules/core-java-lang-oop-generics/README.md

@@ -8,3 +8,4 @@ This module contains articles about generics in Java
 - [Raw Types in Java](https://www.baeldung.com/raw-types-java)
 - [Super Type Tokens in Java Generics](https://www.baeldung.com/java-super-type-tokens)
 - [Java Warning “unchecked conversion”](https://www.baeldung.com/java-unchecked-conversion)
+- [Java Warning “Unchecked Cast”](https://www.baeldung.com/java-warning-unchecked-cast)

core-java-modules/core-java-lang-oop-generics/src/main/java/com/baeldung/uncheckedcast/UncheckedCast.java

@@ -0,0 +1,26 @@
+package com.baeldung.uncheckedcast;
+
+import java.time.LocalDate;
+import java.time.Month;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
+
+public class UncheckedCast {
+    public static Map getRawMap() {
+        Map rawMap = new HashMap();
+        rawMap.put("date 1", LocalDate.of(2021, Month.FEBRUARY, 10));
+        rawMap.put("date 2", LocalDate.of(1992, Month.AUGUST, 8));
+        rawMap.put("date 3", LocalDate.of(1976, Month.NOVEMBER, 18));
+        return rawMap;
+    }
+
+    public static Map getRawMapWithMixedTypes() {
+        Map rawMap = new HashMap();
+        rawMap.put("date 1", LocalDate.of(2021, Month.FEBRUARY, 10));
+        rawMap.put("date 2", LocalDate.of(1992, Month.AUGUST, 8));
+        rawMap.put("date 3", LocalDate.of(1976, Month.NOVEMBER, 18));
+        rawMap.put("date 4", new Date());
+        return rawMap;
+    }
+}

core-java-modules/core-java-lang-oop-generics/src/test/java/com/baeldung/uncheckedcast/UncheckedCastUnitTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.uncheckedcast;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.time.LocalDate;
+import java.time.Month;
+import java.util.Map;
+
+public class UncheckedCastUnitTest {
+
+    @Test
+    public void givenRawMap_whenCastToTypedMap_shouldHaveCompilerWarning() {
+        Map<String, LocalDate> castFromRawMap = (Map<String, LocalDate>) UncheckedCast.getRawMap();
+        Assert.assertEquals(3, castFromRawMap.size());
+        Assert.assertEquals(castFromRawMap.get("date 2"), LocalDate.of(1992, Month.AUGUST, 8));
+    }
+
+    @Test(expected = ClassCastException.class)
+    public void givenMixTypedRawMap_whenCastToTypedMap_shouldThrowClassCastException() {
+        Map<String, LocalDate> castFromRawMap = (Map<String, LocalDate>) UncheckedCast.getRawMapWithMixedTypes();
+        Assert.assertEquals(4, castFromRawMap.size());
+        Assert.assertTrue(castFromRawMap.get("date 4").isAfter(castFromRawMap.get("date 3")));
+    }
+}

core-java-modules/core-java-nio-2/pom.xml

@@ -14,5 +14,12 @@
         <version>0.0.1-SNAPSHOT</version>
         <relativePath>../</relativePath>
     </parent>
-
+    <dependencies>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.6.1</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
 </project>

core-java-modules/core-java-nio-2/src/test/java/com/baeldung/selector/SelectorManualTest.java

@@ -0,0 +1,64 @@
+package com.baeldung.selector;
+
+import org.junit.Test;
+import java.io.IOException;
+import java.nio.channels.Pipe;
+import java.nio.channels.SelectableChannel;
+import java.nio.channels.Selector;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import static java.nio.channels.SelectionKey.OP_READ;
+
+public class SelectorManualTest {
+
+    @Test
+    public void whenWakeUpCalledOnSelector_thenBlockedThreadReturns() throws IOException, InterruptedException {
+        Pipe pipe = Pipe.open();
+
+        Selector selector = Selector.open();
+        SelectableChannel channel = pipe.source();
+        channel.configureBlocking(false);
+        channel.register(selector, OP_READ);
+
+        List<String> invocationStepsTracker = Collections.synchronizedList(new ArrayList<>());
+
+        CountDownLatch latch = new CountDownLatch(1);
+
+        Thread thread = new Thread(() -> {
+            invocationStepsTracker.add(">> Count down");
+            latch.countDown();
+            try {
+                invocationStepsTracker.add(">> Start select");
+                selector.select();
+                invocationStepsTracker.add(">> End select");
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        });
+
+        invocationStepsTracker.add(">> Start await");
+        thread.start();
+        latch.await();
+        invocationStepsTracker.add(">> End await");
+
+        invocationStepsTracker.add(">> Wakeup thread");
+
+        selector.wakeup();
+        channel.close();
+
+        assertThat(invocationStepsTracker)
+          .containsExactly(
+            ">> Start await",
+            ">> Count down",
+            ">> Start select",
+            ">> End await",
+            ">> Wakeup thread",
+            ">> End select"
+          );
+    }
+}

docker/README.md

@@ -3,3 +3,4 @@
 - [Introduction to Docker Compose](https://www.baeldung.com/docker-compose)
 - [Reusing Docker Layers with Spring Boot](https://www.baeldung.com/docker-layers-spring-boot)
 - [Running Spring Boot with PostgreSQL in Docker Compose](https://www.baeldung.com/spring-boot-postgresql-docker)
+- [How To Configure Java Heap Size Inside a Docker Container](https://www.baeldung.com/ops/docker-jvm-heap-size)

docker/heap-sizing/Dockerfile

@@ -0,0 +1,4 @@
+FROM openjdk:8u92-jdk-alpine
+COPY /src /src/
+RUN mkdir /app && ls /src && javac /src/main/java/com/baeldung/docker/heapsizing/PrintXmxXms.java -d /app
+CMD java -version && java $JAVA_OPTS -cp /app com.baeldung.docker.heapsizing.PrintXmxXms

docker/heap-sizing/pom.xml

@@ -0,0 +1,61 @@
+<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.4.2</version>
+        <relativePath/> <!-- lookup parent from repository -->
+    </parent>
+    <groupId>com.baeldung.docker</groupId>
+    <artifactId>heap-sizing</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>heap-sizing</name>
+    <description>Demo project for Spring Boot</description>
+    <properties>
+        <java.version>11</java.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-webflux</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.projectreactor</groupId>
+            <artifactId>reactor-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <configuration>
+                    <image>
+                        <name>heapsizing-demo</name>
+                    </image>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>com.google.cloud.tools</groupId>
+                <artifactId>jib-maven-plugin</artifactId>
+                <version>2.7.1</version>
+
+                <configuration>
+                    <to>
+                        <image>heapsizing-demo-jib</image>
+                    </to>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

docker/heap-sizing/src/main/java/com/baeldung/docker/heapsizing/HeapSizingApplication.java

@@ -0,0 +1,19 @@
+package com.baeldung.docker.heapsizing;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+import java.util.logging.Logger;
+
+import static com.baeldung.docker.heapsizing.PrintXmxXms.logMemory;
+
+@SpringBootApplication
+public class HeapSizingApplication {
+    private static final Logger logger = Logger.getLogger(HeapSizingApplication.class.getName());
+
+    public static void main(String[] args) {
+        SpringApplication.run(HeapSizingApplication.class, args);
+        logMemory(logger);
+    }
+
+}

docker/heap-sizing/src/main/java/com/baeldung/docker/heapsizing/PrintXmxXms.java

@@ -0,0 +1,36 @@
+package com.baeldung.docker.heapsizing;
+
+import java.lang.management.ManagementFactory;
+import java.lang.management.MemoryMXBean;
+import java.lang.management.MemoryPoolMXBean;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class PrintXmxXms {
+
+    private static final Logger logger = Logger.getLogger(PrintXmxXms.class.getName());
+
+    public static void main(String[] args) {
+        logMemory(logger);
+    }
+
+    /**
+     * We're reusing this method in HeapSizingApplication, therefore this method was extracted
+     * to avoid repetition.
+     */
+    static void logMemory(Logger logger) {
+        float mb = 1024f * 1024f;
+        MemoryMXBean memoryBean = ManagementFactory.getMemoryMXBean();
+
+        // xmx controls the maximum size of the memory allocation pool,
+        // which includes the heap, the garbage collector's survivor space, and other pools.
+        float xmx = memoryBean.getHeapMemoryUsage().getMax() / mb;
+        float xms = memoryBean.getHeapMemoryUsage().getInit() / mb;
+        logger.log(Level.INFO, "Initial Memory (xms) : {0}mb", xms);
+        logger.log(Level.INFO, "Max Memory (xmx) : {0}mb", xmx);
+
+        for (MemoryPoolMXBean mp : ManagementFactory.getMemoryPoolMXBeans()) {
+            logger.log(Level.INFO, "Pool: {0} (type {1}) = {2}", new Object[]{ mp.getName(), mp.getType(), mp.getUsage().getMax() / mb });
+        }
+    }
+}

guest/core-kotlin/README.md

@@ -1,3 +1,3 @@
 ### Relevant Articles:
 
-- [Kotlin vs Java](https://www.baeldung.com/kotlin/kotlin-vs-java)
+- [Kotlin vs Java](https://www.baeldung.com/kotlin/vs-java)

java-collections-maps-3/src/main/java/com/baeldung/map/hashing/Member.java

@@ -0,0 +1,6 @@
+package com.baeldung.map.hashing;
+
+class Member {
+    Integer id;
+    String name;
+}

java-collections-maps-3/src/main/java/com/baeldung/map/hashing/MemberWithBadHashing.java

@@ -0,0 +1,8 @@
+package com.baeldung.map.hashing;
+
+public class MemberWithBadHashing extends Member {
+    @Override
+    public int hashCode() {
+        return name.hashCode();
+    }
+}

java-collections-maps-3/src/main/java/com/baeldung/map/hashing/MemberWithGuavaHashing.java

@@ -0,0 +1,18 @@
+package com.baeldung.map.hashing;
+
+import com.google.common.base.Charsets;
+import com.google.common.hash.HashFunction;
+import com.google.common.hash.Hashing;
+
+public class MemberWithGuavaHashing extends Member {
+    @Override
+    public int hashCode() {
+        HashFunction hashFunction = Hashing.murmur3_32();
+        return hashFunction.newHasher()
+                .putInt(id)
+                .putString(name, Charsets.UTF_8)
+                .hash().hashCode();
+    }
+
+
+}

java-collections-maps-3/src/main/java/com/baeldung/map/hashing/MemberWithId.java

@@ -0,0 +1,18 @@
+package com.baeldung.map.hashing;
+
+public class MemberWithId extends Member {
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        MemberWithId that = (MemberWithId) o;
+
+        return id.equals(that.id);
+    }
+
+    @Override
+    public int hashCode() {
+        return id;
+    }
+}

java-collections-maps-3/src/main/java/com/baeldung/map/hashing/MemberWithIdAndName.java

@@ -0,0 +1,23 @@
+package com.baeldung.map.hashing;
+
+import java.util.Objects;
+
+public class MemberWithIdAndName extends Member {
+    public static final int PRIME = 31;
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        MemberWithObjects that = (MemberWithObjects) o;
+        return Objects.equals(id, that.id) &&
+                Objects.equals(name, that.name);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = id.hashCode();
+        result = PRIME * result + (name == null ? 0  : name.hashCode());
+        return result;
+    }
+}

java-collections-maps-3/src/main/java/com/baeldung/map/hashing/MemberWithObjects.java

@@ -0,0 +1,19 @@
+package com.baeldung.map.hashing;
+
+import java.util.Objects;
+
+public class MemberWithObjects extends Member {
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        MemberWithObjects that = (MemberWithObjects) o;
+        return Objects.equals(id, that.id) &&
+                Objects.equals(name, that.name);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, name);
+    }
+}

java-collections-maps-3/src/test/java/com/baeldung/map/hashing/HashingUnitTest.java

@@ -0,0 +1,76 @@
+package com.baeldung.map.hashing;
+
+import com.google.common.base.Stopwatch;
+import org.junit.jupiter.api.Test;
+
+import java.time.Duration;
+import java.util.HashMap;
+import java.util.SplittableRandom;
+import java.util.function.Supplier;
+
+public class HashingUnitTest {
+
+    public static final int SAMPLES = 1000000;
+    private SplittableRandom random = new SplittableRandom();
+
+    private String[] names = {"John", "Adam", "Suzie"};
+
+    @Test
+    void givenPrimitiveByteArrayKey_whenRetrievingFromMap_shouldRetrieveDifferentObjects() {
+        // bad hashing example is prohibitively slow for bigger samples
+//        Duration[] badHashing = testDuration(MemberWithBadHashing::new);
+        Duration[] withId = testDuration(MemberWithId::new);
+        Duration[] withObjects = testDuration(MemberWithObjects::new);
+        Duration[] withIdAndName = testDuration(MemberWithIdAndName::new);
+
+//        System.out.println("Inserting with bad hashing:");
+//        System.out.println(badHashing[0]);
+//        System.out.println("Getting with bad hashing:");
+//        System.out.println(badHashing[1]);
+
+        System.out.println("Inserting with id hashing:");
+        System.out.println(withId[0]);
+        System.out.println("Getting with id hashing:");
+        System.out.println(withId[1]);
+
+        System.out.println("Inserting with id and name hashing:");
+        System.out.println(withIdAndName[0]);
+        System.out.println("Getting with id and name hashing:");
+        System.out.println(withIdAndName[1]);
+
+        System.out.println("Inserting with Objects hashing:");
+        System.out.println(withObjects[0]);
+        System.out.println("Getting with Objects hashing:");
+        System.out.println(withObjects[1]);
+    }
+
+    private String randomName() {
+        return names[random.nextInt(2)];
+    }
+
+    private <T extends Member> Duration[] testDuration(Supplier<T> factory) {
+        HashMap<T, String> map = new HashMap<>();
+        Stopwatch stopwatch = Stopwatch.createUnstarted();
+
+        stopwatch.start();
+        for(int i = 0; i < SAMPLES; i++) {
+            T member = factory.get();
+            member.id = i;
+            member.name = randomName();
+            map.put(member, member.name);
+        }
+        stopwatch.stop();
+        Duration elapsedInserting = stopwatch.elapsed();
+        stopwatch.reset();
+
+        stopwatch.start();
+        for (T key : map.keySet()) {
+            map.get(key);
+        }
+        stopwatch.stop();
+        Duration elapsedGetting = stopwatch.elapsed();
+        stopwatch.reset();
+
+        return new Duration[]{elapsedInserting, elapsedGetting};
+    }
+}

jmeter/README.md

@@ -7,7 +7,7 @@ It contains the code of a simple API for some CRUD operations built using Spring
 
 - Maven
 - JDK 8
-- MongoDB
+- MongoDB (Note: for the Write Extracted Data to a File Using JMeter example MongoDB is not required)
 
 ### Running
 
@@ -36,6 +36,14 @@ Or create a new one via a POST:
 $ curl -X POST -H "Content-Type:application/json" -d '{ "firstName" : "Dassi", "lastName" : "Orleando", "phoneNumber": "+237 545454545", "email": "mymail@yahoo.fr" }' localhost:8080/students
 ```
 
+### Available UUID API
+
+You can view the test response using curl:
+
+```bash
+$ curl localhost:8080/api/uuid
+```
+
 Now with default configurations it will be available at: [http://localhost:8080](http://localhost:8080)
 
 Enjoy it :)

jmeter/src/main/java/com/baeldung/controller/RetrieveUuidController.java

@@ -0,0 +1,18 @@
+package com.baeldung.controller;
+
+import com.baeldung.model.Response;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.UUID;
+
+import static java.lang.String.format;
+
+@RestController
+public class RetrieveUuidController {
+
+    @GetMapping("/api/uuid")
+    public Response uuid() {
+        return new Response(format("Test message... %s.", UUID.randomUUID()));
+    }
+}

jmeter/src/main/java/com/baeldung/model/Response.java

@@ -0,0 +1,40 @@
+package com.baeldung.model;
+
+import java.time.Instant;
+import java.util.UUID;
+
+public class Response {
+    private Instant timestamp;
+    private UUID uuid;
+    private String message;
+
+    public Response(String message) {
+        this.timestamp = Instant.now();
+        this.uuid = UUID.randomUUID();
+        this.message = message;
+    }
+
+    public Instant getTimestamp() {
+        return timestamp;
+    }
+
+    public void setTimestamp(Instant timestamp) {
+        this.timestamp = timestamp;
+    }
+
+    public UUID getUuid() {
+        return uuid;
+    }
+
+    public void setUuid(UUID uuid) {
+        this.uuid = uuid;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+}

jmeter/src/main/resources/FileExtractionExample.jmx

@@ -0,0 +1,124 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<jmeterTestPlan version="1.2" properties="5.0" jmeter="5.4.1">
+  <hashTree>
+    <TestPlan guiclass="TestPlanGui" testclass="TestPlan" testname="Test Plan" enabled="true">
+      <stringProp name="TestPlan.comments">To run this test plan you must also be running the Spring application &quot;JmeterApplication&quot; That can be found in this directory</stringProp>
+      <boolProp name="TestPlan.functional_mode">false</boolProp>
+      <boolProp name="TestPlan.tearDown_on_shutdown">true</boolProp>
+      <boolProp name="TestPlan.serialize_threadgroups">false</boolProp>
+      <elementProp name="TestPlan.user_defined_variables" elementType="Arguments" guiclass="ArgumentsPanel" testclass="Arguments" testname="User Defined Variables" enabled="true">
+        <collectionProp name="Arguments.arguments"/>
+      </elementProp>
+      <stringProp name="TestPlan.user_define_classpath"></stringProp>
+    </TestPlan>
+    <hashTree>
+      <ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group" enabled="true">
+        <stringProp name="ThreadGroup.on_sample_error">continue</stringProp>
+        <elementProp name="ThreadGroup.main_controller" elementType="LoopController" guiclass="LoopControlPanel" testclass="LoopController" testname="Loop Controller" enabled="true">
+          <boolProp name="LoopController.continue_forever">false</boolProp>
+          <stringProp name="LoopController.loops">1</stringProp>
+        </elementProp>
+        <stringProp name="ThreadGroup.num_threads">1</stringProp>
+        <stringProp name="ThreadGroup.ramp_time">1</stringProp>
+        <boolProp name="ThreadGroup.scheduler">false</boolProp>
+        <stringProp name="ThreadGroup.duration"></stringProp>
+        <stringProp name="ThreadGroup.delay"></stringProp>
+        <boolProp name="ThreadGroup.same_user_on_next_iteration">true</boolProp>
+      </ThreadGroup>
+      <hashTree>
+        <HTTPSamplerProxy guiclass="HttpTestSampleGui" testclass="HTTPSamplerProxy" testname="Call GET Test endpoint " enabled="true">
+          <elementProp name="HTTPsampler.Arguments" elementType="Arguments" guiclass="HTTPArgumentsPanel" testclass="Arguments" testname="User Defined Variables" enabled="true">
+            <collectionProp name="Arguments.arguments"/>
+          </elementProp>
+          <stringProp name="HTTPSampler.domain">localhost</stringProp>
+          <stringProp name="HTTPSampler.port">8080</stringProp>
+          <stringProp name="HTTPSampler.protocol">http</stringProp>
+          <stringProp name="HTTPSampler.contentEncoding"></stringProp>
+          <stringProp name="HTTPSampler.path">/api/test</stringProp>
+          <stringProp name="HTTPSampler.method">GET</stringProp>
+          <boolProp name="HTTPSampler.follow_redirects">true</boolProp>
+          <boolProp name="HTTPSampler.auto_redirects">false</boolProp>
+          <boolProp name="HTTPSampler.use_keepalive">true</boolProp>
+          <boolProp name="HTTPSampler.DO_MULTIPART_POST">false</boolProp>
+          <stringProp name="HTTPSampler.embedded_url_re"></stringProp>
+          <stringProp name="HTTPSampler.connect_timeout"></stringProp>
+          <stringProp name="HTTPSampler.response_timeout"></stringProp>
+        </HTTPSamplerProxy>
+        <hashTree>
+          <JSONPostProcessor guiclass="JSONPostProcessorGui" testclass="JSONPostProcessor" testname="JSON Extractor" enabled="true">
+            <stringProp name="JSONPostProcessor.referenceNames">message</stringProp>
+            <stringProp name="JSONPostProcessor.jsonPathExprs">$.message</stringProp>
+            <stringProp name="JSONPostProcessor.match_numbers">1</stringProp>
+            <boolProp name="JSONPostProcessor.compute_concat">true</boolProp>
+            <stringProp name="JSONPostProcessor.defaultValues">NOT_FOUND</stringProp>
+          </JSONPostProcessor>
+          <hashTree/>
+          <BeanShellPostProcessor guiclass="TestBeanGUI" testclass="BeanShellPostProcessor" testname="Response to file using BeanShell PostProcessor" enabled="true">
+            <stringProp name="filename"></stringProp>
+            <stringProp name="parameters"></stringProp>
+            <boolProp name="resetInterpreter">false</boolProp>
+            <stringProp name="script">FileWriter fWriter = new FileWriter(&quot;<path>/result.txt&quot;, true);
+BufferedWriter buff = new BufferedWriter(fWriter);
+
+buff.write(&quot;Response Code : &quot; + ctx.getPreviousResult().getResponseCode());
+buff.write(System.getProperty(&quot;line.separator&quot;));
+buff.write(&quot;Response Headers : &quot; + ctx.getPreviousResult().getResponseHeaders());
+buff.write(System.getProperty(&quot;line.separator&quot;));
+buff.write(&quot;Response Body : &quot; + new String(ctx.getPreviousResult().getResponseData()));
+
+buff.write(&quot;More complex extraction : &quot; + vars.get(&quot;message&quot;));
+
+buff.close();
+fWriter.close();</stringProp>
+          </BeanShellPostProcessor>
+          <hashTree/>
+          <ResultSaver guiclass="ResultSaverGui" testclass="ResultSaver" testname="Response to file using file write Listener" enabled="true">
+            <stringProp name="FileSaver.filename">response</stringProp>
+            <boolProp name="FileSaver.errorsonly">false</boolProp>
+            <boolProp name="FileSaver.successonly">false</boolProp>
+            <boolProp name="FileSaver.skipsuffix">false</boolProp>
+            <boolProp name="FileSaver.skipautonumber">false</boolProp>
+          </ResultSaver>
+          <hashTree/>
+        </hashTree>
+        <ResultCollector guiclass="ViewResultsFullVisualizer" testclass="ResultCollector" testname="View Results Tree" enabled="true">
+          <boolProp name="ResultCollector.error_logging">false</boolProp>
+          <objProp>
+            <name>saveConfig</name>
+            <value class="SampleSaveConfiguration">
+              <time>true</time>
+              <latency>true</latency>
+              <timestamp>true</timestamp>
+              <success>true</success>
+              <label>true</label>
+              <code>true</code>
+              <message>true</message>
+              <threadName>true</threadName>
+              <dataType>true</dataType>
+              <encoding>false</encoding>
+              <assertions>true</assertions>
+              <subresults>true</subresults>
+              <responseData>false</responseData>
+              <samplerData>false</samplerData>
+              <xml>false</xml>
+              <fieldNames>true</fieldNames>
+              <responseHeaders>false</responseHeaders>
+              <requestHeaders>false</requestHeaders>
+              <responseDataOnError>false</responseDataOnError>
+              <saveAssertionResultsFailureMessage>true</saveAssertionResultsFailureMessage>
+              <assertionsResultsToSave>0</assertionsResultsToSave>
+              <bytes>true</bytes>
+              <sentBytes>true</sentBytes>
+              <url>true</url>
+              <threadCounts>true</threadCounts>
+              <idleTime>true</idleTime>
+              <connectTime>true</connectTime>
+            </value>
+          </objProp>
+          <stringProp name="filename"></stringProp>
+        </ResultCollector>
+        <hashTree/>
+      </hashTree>
+    </hashTree>
+  </hashTree>
+</jmeterTestPlan>

jmeter/src/test/java/com/baeldung/JmeterIntegrationTest.java

@@ -0,0 +1,35 @@
+package com.baeldung;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.context.WebApplicationContext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@SpringBootTest
+class JmeterIntegrationTest {
+
+    MockMvc mvc;
+
+    public JmeterIntegrationTest(WebApplicationContext wac) {
+        this.mvc = MockMvcBuilders.webAppContextSetup(wac).build();
+    }
+
+    @Test
+    void whenCallingUUIDController_thenWeShouldRecieveRandomizedResponse() throws Exception {
+        MockHttpServletResponse response = mvc.perform(get("/api/uuid"))
+          .andDo(print())
+          .andExpect(status().isOk())
+          .andReturn()
+          .getResponse();
+
+        assertThat(response.getContentAsString())
+          .contains("Test message...");
+    }
+}

maven-modules/pom.xml

@@ -27,6 +27,7 @@
         <module>versions-maven-plugin</module>
         <module>version-collision</module>
         <module>optional-dependencies</module>
+        <module>version-overriding-plugins</module>
     </modules>
 
 </project>

maven-modules/version-overriding-plugins/README.md

@@ -0,0 +1,5 @@
+Use `` mvn help:effective-pom`` to see the final generated pom.
+
+### Relevant Articles:
+
+- [Override Maven Plugin Configuration from Parent](https://www.baeldung.com/maven-plugin-override-parent)

maven-modules/version-overriding-plugins/child-a/pom.xml

@@ -0,0 +1,36 @@
+<?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">
+    <parent>
+        <artifactId>version-overriding-plugins</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+    <packaging>pom</packaging>
+
+    <artifactId>child-a</artifactId>
+    <build>
+        <plugins>
+            <plugin>
+                <artifactId>maven-resources-plugin</artifactId>
+                <configuration>
+                    <resources combine.self="override">
+                        <resource>
+                            <directory>child-a-resources</directory>
+                        </resource>
+                    </resources>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

maven-modules/version-overriding-plugins/child-b/pom.xml

@@ -0,0 +1,15 @@
+<?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">
+    <parent>
+        <artifactId>version-overriding-plugins</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>child-b</artifactId>
+
+
+</project>

maven-modules/version-overriding-plugins/pom.xml

@@ -0,0 +1,55 @@
+<?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">
+    <parent>
+        <artifactId>maven-modules</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+    <properties>
+        <maven.compiler.plugin>3.8.0</maven.compiler.plugin>
+    </properties>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>version-overriding-plugins</artifactId>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>child-a</module>
+        <module>child-b</module>
+    </modules>
+
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-compiler-plugin</artifactId>
+                    <version>${maven.compiler.plugin}</version>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+        <plugins>
+            <plugin>
+                <artifactId>maven-resources-plugin</artifactId>
+                <configuration>
+                    <resources combine.children="append">
+                        <resource>
+                            <directory>parent-resources</directory>
+                        </resource>
+                    </resources>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>11</source>
+                    <target>11</target>
+                    <maxmem>512m</maxmem>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

pom.xml

@@ -631,6 +631,7 @@
                 <module>spring-core-2</module>
                 <module>spring-core-3</module>
                 <module>spring-core-4</module>
+                <module>spring-core-5</module>
                 <module>spring-cucumber</module>
 
                 <module>spring-data-rest</module>
@@ -1082,6 +1083,7 @@
                 <module>spring-core-2</module>
                 <module>spring-core-3</module>
                 <module>spring-core-4</module>
+                <module>spring-core-5</module>
                 <module>spring-cucumber</module>
 
                 <module>spring-data-rest</module>

spring-5-reactive-client/README.md

@@ -8,7 +8,6 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
 ### Relevant Articles
 - [Logging Spring WebClient Calls](https://www.baeldung.com/spring-log-webclient-calls)
 - [Simultaneous Spring WebClient Calls](https://www.baeldung.com/spring-webclient-simultaneous-calls)
-- [Logging Spring WebClient Calls](https://www.baeldung.com/spring-log-webclient-calls)
 - [Mocking a WebClient in Spring](https://www.baeldung.com/spring-mocking-webclient)
 - [Spring WebClient Filters](https://www.baeldung.com/spring-webclient-filters)
 - [Get List of JSON Objects with WebClient](https://www.baeldung.com/spring-webclient-json-list)

spring-5-reactive-client/pom.xml

@@ -176,7 +176,6 @@
         <commons-collections4.version>4.1</commons-collections4.version>
         <jetty-reactive-httpclient.version>1.0.3</jetty-reactive-httpclient.version>
         <okhttp.version>4.0.1</okhttp.version>
-        <spring-boot.version>2.3.3.RELEASE</spring-boot.version>
     </properties>
 
 </project>

spring-5-reactive-client/src/main/resources/application.properties

@@ -1,3 +1,5 @@
 logging.level.root=INFO
 
-server.port=8081
+server.port=8081
+
+logging.level.reactor.netty.http.client.HttpClient=DEBUG

spring-5-reactive-client/src/test/java/com/baeldung/reactive/logging/WebClientLoggingIntegrationTest.java

@@ -1,13 +1,13 @@
 package com.baeldung.reactive.logging;
 
-import ch.qos.logback.classic.spi.LoggingEvent;
-import ch.qos.logback.core.Appender;
-import com.baeldung.reactive.logging.filters.LogFilters;
-import com.baeldung.reactive.logging.netty.CustomLogger;
-import com.fasterxml.jackson.databind.ObjectMapper;
+import static com.baeldung.reactive.logging.jetty.RequestLogEnhancer.enhance;
+import static org.mockito.ArgumentMatchers.argThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
 import java.net.URI;
-import lombok.AllArgsConstructor;
-import lombok.Data;
+
 import org.eclipse.jetty.client.api.Request;
 import org.eclipse.jetty.util.ssl.SslContextFactory;
 import org.junit.jupiter.api.BeforeEach;
@@ -17,14 +17,17 @@ import org.springframework.http.client.reactive.JettyClientHttpConnector;
 import org.springframework.http.client.reactive.ReactorClientHttpConnector;
 import org.springframework.web.reactive.function.BodyInserters;
 import org.springframework.web.reactive.function.client.WebClient;
-import reactor.netty.channel.BootstrapHandlers;
-import reactor.netty.http.client.HttpClient;
 
-import static com.baeldung.reactive.logging.jetty.RequestLogEnhancer.enhance;
-import static org.mockito.ArgumentMatchers.argThat;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.when;
+import com.baeldung.reactive.logging.filters.LogFilters;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import ch.qos.logback.classic.spi.LoggingEvent;
+import ch.qos.logback.core.Appender;
+import io.netty.handler.logging.LogLevel;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import reactor.netty.http.client.HttpClient;
+import reactor.netty.transport.logging.AdvancedByteBufFormat;
 
 
 public class WebClientLoggingIntegrationTest {
@@ -114,21 +117,17 @@ public class WebClientLoggingIntegrationTest {
 
     @Test
     public void givenNettyHttpClientWithCustomLogger_whenEndpointIsConsumed_thenRequestAndResponseBodyLogged() {
+        reactor.netty.http.client.HttpClient httpClient = HttpClient.create()
+            .wiretap("reactor.netty.http.client.HttpClient", LogLevel.DEBUG, AdvancedByteBufFormat.TEXTUAL);
 
-        reactor.netty.http.client.HttpClient httpClient = HttpClient
-          .create()
-          .tcpConfiguration(
-            tc -> tc.bootstrap(
-              b -> BootstrapHandlers.updateLogSupport(b, new CustomLogger(HttpClient.class))));
-        WebClient
-          .builder()
-          .clientConnector(new ReactorClientHttpConnector(httpClient))
-          .build()
-          .post()
-          .uri(sampleUrl)
-          .body(BodyInserters.fromObject(post))
-          .exchange()
-          .block();
+        WebClient.builder()
+            .clientConnector(new ReactorClientHttpConnector(httpClient))
+            .build()
+            .post()
+            .uri(sampleUrl)
+            .body(BodyInserters.fromObject(post))
+            .exchange()
+            .block();
 
         verify(nettyAppender).doAppend(argThat(argument -> (((LoggingEvent) argument).getFormattedMessage()).contains(sampleResponseBody)));
     }

spring-5-reactive-client/src/test/java/com/baeldung/reactive/logging/netty/CustomLogger.java

@@ -1,42 +0,0 @@
-package com.baeldung.reactive.logging.netty;
-
-import io.netty.buffer.ByteBuf;
-import io.netty.channel.ChannelHandlerContext;
-import io.netty.handler.logging.LoggingHandler;
-import java.nio.charset.Charset;
-
-import static io.netty.util.internal.PlatformDependent.allocateUninitializedArray;
-import static java.lang.Math.max;
-import static java.nio.charset.Charset.defaultCharset;
-
-public class CustomLogger extends LoggingHandler {
-    public CustomLogger(Class<?> clazz) {
-        super(clazz);
-    }
-
-    @Override
-    protected String format(ChannelHandlerContext ctx, String event, Object arg) {
-        if (arg instanceof ByteBuf) {
-            ByteBuf msg = (ByteBuf) arg;
-            return decode(msg, msg.readerIndex(), msg.readableBytes(), defaultCharset());
-        }
-        return super.format(ctx, event, arg);
-    }
-
-    private String decode(ByteBuf src, int readerIndex, int len, Charset charset) {
-        if (len != 0) {
-            byte[] array;
-            int offset;
-            if (src.hasArray()) {
-                array = src.array();
-                offset = src.arrayOffset() + readerIndex;
-            } else {
-                array = allocateUninitializedArray(max(len, 1024));
-                offset = 0;
-                src.getBytes(readerIndex, array, 0, len);
-            }
-            return new String(array, offset, len, charset);
-        }
-        return "";
-    }
-}

spring-5-reactive/src/test/java/com/baeldung/web/client/WebClientIntegrationTest.java

@@ -11,8 +11,6 @@ import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
 import org.junit.jupiter.api.Test;
-import org.reactivestreams.Publisher;
-import org.reactivestreams.Subscriber;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
 import org.springframework.boot.web.server.LocalServerPort;
@@ -41,6 +39,7 @@ import com.baeldung.web.reactive.client.Foo;
 import com.baeldung.web.reactive.client.WebClientApplication;
 
 import io.netty.channel.ChannelOption;
+import io.netty.handler.timeout.ReadTimeoutException;
 import io.netty.handler.timeout.ReadTimeoutHandler;
 import io.netty.handler.timeout.WriteTimeoutHandler;
 import reactor.core.publisher.Mono;
@@ -265,17 +264,18 @@ public class WebClientIntegrationTest {
                 .addHandlerLast(new WriteTimeoutHandler(1000, TimeUnit.MILLISECONDS)));
 
         WebClient timeoutClient = WebClient.builder()
+            .baseUrl("http://localhost:" + port)
             .clientConnector(new ReactorClientHttpConnector(httpClient))
             .build();
 
-        BodyInserter<Publisher<String>, ReactiveHttpOutputMessage> inserterCompleteSuscriber = BodyInserters.fromPublisher(Subscriber::onComplete, String.class);
-        RequestHeadersSpec<?> headersSpecInserterCompleteSuscriber = timeoutClient.post()
+        RequestHeadersSpec<?> neverendingMonoBodyRequest = timeoutClient.post()
             .uri("/resource")
-            .body(inserterCompleteSuscriber);
+            .body(Mono.never(), String.class);
 
-        StepVerifier.create(headersSpecInserterCompleteSuscriber.retrieve()
+        StepVerifier.create(neverendingMonoBodyRequest.retrieve()
             .bodyToMono(String.class))
-            .expectTimeout(Duration.ofMillis(2000))
+            .expectErrorMatches(ex -> WebClientRequestException.class.isAssignableFrom(ex.getClass()) && ReadTimeoutException.class.isAssignableFrom(ex.getCause()
+                .getClass()))
             .verify();
     }
 

spring-5/README.md

@@ -11,3 +11,5 @@ This module contains articles about Spring 5
 - [Spring Assert Statements](https://www.baeldung.com/spring-assert)
 - [Difference between \<context:annotation-config> vs \<context:component-scan>](https://www.baeldung.com/spring-contextannotation-contextcomponentscan)
 - [Finding the Spring Version](https://www.baeldung.com/spring-find-version)
+- [Spring 5 Testing with @EnabledIf Annotation](https://www.baeldung.com/spring-5-enabledIf)
+- [Configuring a Hikari Connection Pool with Spring Boot](https://www.baeldung.com/spring-boot-hikari)

spring-5/src/test/java/com/baeldung/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Concurrent Test Execution in Spring 5](https://www.baeldung.com/spring-5-concurrent-tests)

spring-boot-modules/pom.xml

@@ -54,6 +54,7 @@
         <module>spring-boot-mvc-2</module>
         <module>spring-boot-mvc-3</module>
         <module>spring-boot-mvc-birt</module>
+        <module>spring-boot-mvc-jersey</module>
         <module>spring-boot-nashorn</module>
         <module>spring-boot-parent</module>
         <module>spring-boot-performance</module>

spring-boot-modules/spring-boot-admin/spring-boot-admin-client/pom.xml

@@ -61,7 +61,7 @@
     </build>
 
     <properties>
-        <spring-boot-admin-starter-client.version>2.2.2</spring-boot-admin-starter-client.version>
+        <spring-boot-admin-starter-client.version>2.4.0</spring-boot-admin-starter-client.version>
         <spring-boot-maven-plugin.version>2.0.4.RELEASE</spring-boot-maven-plugin.version>
     </properties>
 </project>

spring-boot-modules/spring-boot-admin/spring-boot-admin-server/pom.xml

@@ -82,10 +82,9 @@
     </build>
 
     <properties>
-        <spring-boot-admin-server.version>2.2.2</spring-boot-admin-server.version>
-        <spring-boot-admin-starter-client.version>2.2.2</spring-boot-admin-starter-client.version>
+        <spring-boot-admin-server.version>2.4.0</spring-boot-admin-server.version>
+        <spring-boot-admin-starter-client.version>2.4.0</spring-boot-admin-starter-client.version>
         <spring-boot-admin-server-ui-login.version>1.5.7</spring-boot-admin-server-ui-login.version>
         <spring-boot-maven-plugin.version>2.0.4.RELEASE</spring-boot-maven-plugin.version>
-        <spring-boot.version>2.3.3.RELEASE</spring-boot.version>
     </properties>
 </project>

spring-boot-modules/spring-boot-admin/spring-boot-admin-server/src/main/java/com/baeldung/springbootadminserver/SpringBootAdminServerApplication.java

@@ -1,11 +1,12 @@
 package com.baeldung.springbootadminserver;
 
+import de.codecentric.boot.admin.server.config.AdminServerHazelcastAutoConfiguration;
 import de.codecentric.boot.admin.server.config.EnableAdminServer;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 
 @EnableAdminServer
-@SpringBootApplication
+@SpringBootApplication(exclude = AdminServerHazelcastAutoConfiguration.class)
 public class SpringBootAdminServerApplication {
 
     public static void main(String[] args) {

spring-boot-modules/spring-boot-admin/spring-boot-admin-server/src/main/java/com/baeldung/springbootadminserver/configs/HazelcastConfig.java

@@ -1,12 +1,13 @@
 package com.baeldung.springbootadminserver.configs;
 
 import com.hazelcast.config.Config;
+import com.hazelcast.config.EvictionConfig;
 import com.hazelcast.config.EvictionPolicy;
 import com.hazelcast.config.InMemoryFormat;
 import com.hazelcast.config.MapConfig;
 import com.hazelcast.config.MergePolicyConfig;
 import com.hazelcast.config.TcpIpConfig;
-import com.hazelcast.map.merge.PutIfAbsentMapMergePolicy;
+import com.hazelcast.spi.merge.PutIfAbsentMergePolicy;
 
 import java.util.Collections;
 
@@ -16,32 +17,27 @@ import org.springframework.context.annotation.Configuration;
 @Configuration
 public class HazelcastConfig {
 
-    @Bean
-    public Config hazelcast() {
-        MapConfig eventStoreMap = new MapConfig("spring-boot-admin-event-store").setInMemoryFormat(InMemoryFormat.OBJECT)
-            .setBackupCount(1)
-            .setEvictionPolicy(EvictionPolicy.NONE)
-            .setMergePolicyConfig(new MergePolicyConfig(PutIfAbsentMapMergePolicy.class.getName(), 100));
+	@Bean
+	public Config hazelcast() {
+		MapConfig eventStoreMap = new MapConfig("spring-boot-admin-event-store")
+				.setInMemoryFormat(InMemoryFormat.OBJECT).setBackupCount(1)
+				.setEvictionConfig(new EvictionConfig().setEvictionPolicy(EvictionPolicy.NONE))
+				.setMergePolicyConfig(new MergePolicyConfig(PutIfAbsentMergePolicy.class.getName(), 100));
 
-        MapConfig sentNotificationsMap = new MapConfig("spring-boot-admin-application-store").setInMemoryFormat(InMemoryFormat.OBJECT)
-            .setBackupCount(1)
-            .setEvictionPolicy(EvictionPolicy.LRU)
-            .setMergePolicyConfig(new MergePolicyConfig(PutIfAbsentMapMergePolicy.class.getName(), 100));
+		MapConfig sentNotificationsMap = new MapConfig("spring-boot-admin-application-store")
+				.setInMemoryFormat(InMemoryFormat.OBJECT).setBackupCount(1)
+				.setEvictionConfig(new EvictionConfig().setEvictionPolicy(EvictionPolicy.LRU))
+				.setMergePolicyConfig(new MergePolicyConfig(PutIfAbsentMergePolicy.class.getName(), 100));
 
-        Config config = new Config();
-        config.addMapConfig(eventStoreMap);
-        config.addMapConfig(sentNotificationsMap);
-        config.setProperty("hazelcast.jmx", "true");
+		Config config = new Config();
+		config.addMapConfig(eventStoreMap);
+		config.addMapConfig(sentNotificationsMap);
+		config.setProperty("hazelcast.jmx", "true");
 
-        config.getNetworkConfig()
-            .getJoin()
-            .getMulticastConfig()
-            .setEnabled(false);
-        TcpIpConfig tcpIpConfig = config.getNetworkConfig()
-            .getJoin()
-            .getTcpIpConfig();
-        tcpIpConfig.setEnabled(true);
-        tcpIpConfig.setMembers(Collections.singletonList("127.0.0.1"));
-        return config;
-    }
+		config.getNetworkConfig().getJoin().getMulticastConfig().setEnabled(false);
+		TcpIpConfig tcpIpConfig = config.getNetworkConfig().getJoin().getTcpIpConfig();
+		tcpIpConfig.setEnabled(true);
+		tcpIpConfig.setMembers(Collections.singletonList("127.0.0.1"));
+		return config;
+	}
 }

spring-boot-modules/spring-boot-data-2/README.md

@@ -1,4 +1,4 @@
 ### Relevant Articles:
 
 - [Spring Boot: Customize the Jackson ObjectMapper](https://www.baeldung.com/spring-boot-customize-jackson-objectmapper)
-- [Configuring a Hikari Connection Pool with Spring Boot](https://www.baeldung.com/spring-boot-hikari)
+- [“HttpMessageNotWritableException: No converter found for return value of type”](https://www.baeldung.com/spring-no-converter-found)

spring-boot-modules/spring-boot-data-2/src/main/java/com/baeldung/boot/noconverterfound/NoConverterFoundApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.boot.noconverterfound;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class NoConverterFoundApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(NoConverterFoundApplication.class, args);
+    }
+}

spring-boot-modules/spring-boot-data-2/src/main/java/com/baeldung/boot/noconverterfound/controller/StudentRestController.java

@@ -0,0 +1,21 @@
+package com.baeldung.boot.noconverterfound.controller;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.baeldung.boot.noconverterfound.model.Student;
+
+@RestController
+@RequestMapping(value = "/api")
+public class StudentRestController {
+
+    @GetMapping("/student/{id}")
+    public ResponseEntity<Student> get(@PathVariable("id") int id) {
+        // Custom logic
+        return ResponseEntity.ok(new Student(id, "John", "Wiliams", "AA"));
+    }
+
+}

spring-boot-modules/spring-boot-data-2/src/main/java/com/baeldung/boot/noconverterfound/model/Student.java

@@ -0,0 +1,53 @@
+package com.baeldung.boot.noconverterfound.model;
+
+public class Student {
+
+    private int id;
+    private String firstName;
+    private String lastName;
+    private String grade;
+
+    public Student() {
+
+    }
+
+    public Student(int id, String firstName, String lastName, String grade) {
+        this.id = id;
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.grade = grade;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getGrade() {
+        return grade;
+    }
+
+    public void setGrade(String grade) {
+        this.grade = grade;
+    }
+
+}

spring-boot-modules/spring-boot-data-2/src/test/java/com/baeldung/boot/noconverterfound/NoConverterFoundIntegrationTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.boot.noconverterfound;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.http.converter.HttpMessageNotWritableException;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.servlet.MockMvc;
+
+import com.baeldung.boot.noconverterfound.controller.StudentRestController;
+
+@RunWith(SpringRunner.class)
+@WebMvcTest(StudentRestController.class)
+public class NoConverterFoundIntegrationTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    /* Remove Getters from Student class to successfully run this test case
+     * @Test
+    public void whenGettersNotDefined_thenThrowException() throws Exception {
+
+        String url = "/api/student/1";
+
+        this.mockMvc.perform(get(url))
+          .andExpect(status().isInternalServerError())
+          .andExpect(result -> assertThat(result.getResolvedException())
+            .isInstanceOf(HttpMessageNotWritableException.class))
+          .andExpect(result -> assertThat(result.getResolvedException().getMessage())
+            .contains("No converter found for return value of type"));
+
+    }
+    */
+
+    @Test
+    public void whenGettersAreDefined_thenReturnObject() throws Exception {
+
+        String url = "/api/student/2";
+
+        this.mockMvc.perform(get(url))
+          .andExpect(status().isOk())
+          .andExpect(jsonPath("$.firstName").value("John"));
+
+    }
+
+}

spring-boot-modules/spring-boot-mvc-jersey/README.md

@@ -0,0 +1,8 @@
+## Spring Boot Admin
+
+This module contains articles about Spring Boot: JAX-RS vs Spring
+
+
+### Relevant Articles: 
+
+- [REST API: JAX-RS vs Spring](https://www.baeldung.com/TBD)

spring-boot-modules/spring-boot-mvc-jersey/pom.xml

@@ -0,0 +1,23 @@
+<?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>
+
+    <parent>
+        <groupId>com.baeldung.spring-boot-modules</groupId>
+        <artifactId>spring-boot-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
+    </parent>
+
+    <artifactId>spring-boot-mvc-jersey</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <packaging>pom</packaging>
+
+    <name>spring-boot-mvc-jersey</name>
+
+    <modules>
+        <module>spring-boot-jersey</module>
+        <module>spring-boot-mvc</module>
+    </modules>
+</project>

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-jersey/pom.xml

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
+         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>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.4.2</version>
+        <relativePath/> <!-- lookup parent from repository -->
+    </parent>
+
+    <groupId>com.baeldung.boot</groupId>
+    <artifactId>spring-boot-jersey</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-jersey</artifactId>
+        </dependency>
+
+        <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>
+        </plugins>
+    </build>
+</project>

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-jersey/src/main/java/com/baeldung/boot/jersey/JerseyApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.boot.jersey;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class JerseyApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(JerseyApplication.class, args);
+    }
+
+}

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-jersey/src/main/java/com/baeldung/boot/jersey/controllers/HelloController.java

@@ -0,0 +1,20 @@
+package com.baeldung.boot.jersey.controllers;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.PathParam;
+import javax.ws.rs.Produces;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+
+@Path("/hello")
+public class HelloController {
+
+    @GET
+    @Path("/{name}")
+    @Produces(MediaType.TEXT_PLAIN)
+    public Response hello(@PathParam("name") String name) {
+        return Response.ok("Hello, " + name).build();
+    }
+
+}

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-jersey/src/main/resources/application.properties

@@ -0,0 +1 @@
+

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-jersey/src/test/java/com/baeldung/boot/jersey/JerseyApplicationIntegrationTests.java

@@ -0,0 +1,13 @@
+package com.baeldung.boot.jersey;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class JerseyApplicationIntegrationTests {
+
+    @Test
+    void contextLoads() {
+    }
+
+}

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-jersey/src/test/java/com/baeldung/boot/jersey/controllers/HelloControllerUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.boot.jersey.controllers;
+
+import javax.ws.rs.core.Response;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+@Import(HelloController.class)
+@ExtendWith(SpringExtension.class)
+public class HelloControllerUnitTest {
+
+    @Autowired
+    private HelloController helloController;
+
+    @Test
+    public void whenHelloIsInvokedWithCaio_thenReturn200AsStatusAndHelloCaioAsBody() {
+        Response response = this.helloController.hello("Caio");
+        assertThat(response.getStatus()).isEqualTo(200);
+        assertThat(response.getEntity()).isEqualTo("Hello, Caio");
+    }
+
+}

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-mvc/pom.xml

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
+         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>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.4.2</version>
+        <relativePath/> <!-- lookup parent from repository -->
+    </parent>
+
+    <groupId>com.baeldung.boot</groupId>
+    <artifactId>spring-boot-mvc</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+
+        <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>
+        </plugins>
+    </build>
+</project>

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-mvc/src/main/java/com/baeldung/boot/mvc/MvcApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.boot.mvc;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class MvcApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(MvcApplication.class, args);
+    }
+
+}

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-mvc/src/main/java/com/baeldung/boot/mvc/controllers/HelloController.java

@@ -0,0 +1,21 @@
+package com.baeldung.boot.mvc.controllers;
+
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/hello")
+public class HelloController {
+
+    @GetMapping(value = "/{name}", produces = MediaType.TEXT_PLAIN_VALUE)
+    public ResponseEntity<?> hello(@PathVariable String name) {
+        return new ResponseEntity<>("Hello, " + name, HttpStatus.OK);
+    }
+
+}

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-mvc/src/main/resources/application.properties

@@ -0,0 +1 @@
+

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-mvc/src/test/java/com/baeldung/boot/mvc/MvcApplicationIntegrationTests.java

@@ -0,0 +1,13 @@
+package com.baeldung.boot.mvc;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class MvcApplicationIntegrationTests {
+
+    @Test
+    void contextLoads() {
+    }
+
+}

spring-boot-modules/spring-boot-mvc-jersey/spring-boot-mvc/src/test/java/com/baeldung/boot/mvc/controllers/HelloControllerUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.boot.mvc.controllers;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Import;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.test.context.junit.jupiter.SpringExtension;
+
+@Import(HelloController.class)
+@ExtendWith(SpringExtension.class)
+public class HelloControllerUnitTest {
+
+    @Autowired
+    private HelloController helloController;
+
+    @Test
+    public void whenHelloIsInvokedWithCaio_thenReturn200AsStatusAndHelloCaioAsBody() {
+        ResponseEntity response = this.helloController.hello("Caio");
+        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+        assertThat(response.getBody()).isEqualTo("Hello, Caio");
+    }
+
+}

spring-boot-modules/spring-boot-runtime-2/README.md

@@ -3,4 +3,4 @@
 This module contains articles about administering a Spring Boot runtime
 
 ### Relevant Articles:									
- - 
+ - [Configure the Heap Size When Starting a Spring Boot Application](https://www.baeldung.com/spring-boot-heap-size)

spring-boot-modules/spring-boot-springdoc/README.md

@@ -2,3 +2,4 @@
 
 - [Documenting a Spring REST API Using OpenAPI 3.0](https://www.baeldung.com/spring-rest-openapi-documentation)
 - [Spring REST Docs vs OpenAPI](https://www.baeldung.com/spring-rest-docs-vs-openapi)
+- [Hiding Endpoints From Swagger Documentation in Spring Boot](https://www.baeldung.com/spring-swagger-hiding-endpoints)

spring-boot-rest/src/main/java/com/baeldung/web/config/MyCustomErrorAttributes.java

@@ -2,6 +2,7 @@ package com.baeldung.web.config;
 
 import java.util.Map;
 
+import org.springframework.boot.web.error.ErrorAttributeOptions;
 import org.springframework.boot.web.servlet.error.DefaultErrorAttributes;
 import org.springframework.stereotype.Component;
 import org.springframework.web.context.request.WebRequest;
@@ -10,8 +11,8 @@ import org.springframework.web.context.request.WebRequest;
 public class MyCustomErrorAttributes extends DefaultErrorAttributes {
 
     @Override
-    public Map<String, Object> getErrorAttributes(WebRequest webRequest, boolean includeStackTrace) {
-        Map<String, Object> errorAttributes = super.getErrorAttributes(webRequest, includeStackTrace);
+    public Map<String, Object> getErrorAttributes(WebRequest webRequest, ErrorAttributeOptions options) {
+        Map<String, Object> errorAttributes = super.getErrorAttributes(webRequest, options);
         errorAttributes.put("locale", webRequest.getLocale()
             .toString());
         errorAttributes.remove("error");

spring-boot-rest/src/main/java/com/baeldung/web/config/MyErrorController.java

@@ -4,7 +4,7 @@ import java.util.Map;
 
 import javax.servlet.http.HttpServletRequest;
 
-import org.springframework.boot.autoconfigure.web.ErrorProperties;
+import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController;
 import org.springframework.boot.web.servlet.error.ErrorAttributes;
 import org.springframework.http.HttpStatus;
@@ -16,13 +16,13 @@ import org.springframework.web.bind.annotation.RequestMapping;
 @Component
 public class MyErrorController extends BasicErrorController {
 
-    public MyErrorController(ErrorAttributes errorAttributes) {
-        super(errorAttributes, new ErrorProperties());
+    public MyErrorController(ErrorAttributes errorAttributes, ServerProperties serverProperties) {
+        super(errorAttributes, serverProperties.getError());
     }
 
     @RequestMapping(produces = MediaType.APPLICATION_XML_VALUE)
     public ResponseEntity<Map<String, Object>> xmlError(HttpServletRequest request) {
-        Map<String, Object> body = getErrorAttributes(request, isIncludeStackTrace(request, MediaType.APPLICATION_XML));
+        Map<String, Object> body = getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.APPLICATION_XML));
         body.put("xmlkey", "the XML response is different!");
         HttpStatus status = getStatus(request);
         return new ResponseEntity<>(body, status);

spring-boot-rest/src/main/java/com/baeldung/web/controller/CustomerController.java

@@ -50,7 +50,7 @@ public class CustomerController {
         }
 
         Link link = linkTo(methodOn(CustomerController.class).getOrdersForCustomer(customerId)).withSelfRel();
-        CollectionModel<Order> result = new CollectionModel<>(orders, link);
+        CollectionModel<Order> result = CollectionModel.of(orders, link);
         return result;
     }
 
@@ -72,7 +72,7 @@ public class CustomerController {
         }
 
         Link link = linkTo(CustomerController.class).withSelfRel();
-        CollectionModel<Customer> result = new CollectionModel<>(allCustomers, link);
+        CollectionModel<Customer> result = CollectionModel.of(allCustomers, link);
         return result;
     }
 

spring-boot-rest/src/main/resources/application.properties

@@ -3,3 +3,4 @@ server.servlet.context-path=/spring-boot-rest
 ### Spring Boot default error handling configurations
 #server.error.whitelabel.enabled=false
 #server.error.include-stacktrace=always
+server.error.include-message=always

spring-boot-rest/src/test/java/com/baeldung/controllers/ExamplePostControllerRequestIntegrationTest.java

@@ -33,7 +33,7 @@ public class ExamplePostControllerRequestIntegrationTest {
 
     @Before
     public void preTest() {
-        MockitoAnnotations.initMocks(this);
+        MockitoAnnotations.openMocks(this);
         mockMvc = MockMvcBuilders
           .standaloneSetup(exampleController)
           .build();

spring-boot-rest/src/test/java/com/baeldung/controllers/ExamplePostControllerResponseIntegrationTest.java

@@ -34,7 +34,7 @@ public class ExamplePostControllerResponseIntegrationTest {
 
     @Before
     public void preTest() {
-        MockitoAnnotations.initMocks(this);
+        MockitoAnnotations.openMocks(this);
         mockMvc = MockMvcBuilders
           .standaloneSetup(exampleController)
           .build();

spring-boot-rest/src/test/java/com/baeldung/web/StudentControllerIntegrationTest.java

@@ -8,12 +8,10 @@ import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.http.MediaType;
 import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.test.web.servlet.MockMvc;
-import org.springframework.web.server.MediaTypeNotSupportedStatusException;
 
 import com.baeldung.web.controller.students.Student;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
-import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.delete;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;

spring-cloud/spring-cloud-openfeign/README.md

@@ -2,3 +2,4 @@
 
 - [Introduction to Spring Cloud OpenFeign](https://www.baeldung.com/spring-cloud-openfeign)
 - [Differences Between Netflix Feign and OpenFeign](https://www.baeldung.com/netflix-feign-vs-openfeign)
+- [File Upload With Open Feign](https://www.baeldung.com/java-feign-file-upload)

spring-cloud/spring-cloud-openfeign/pom.xml

@@ -37,12 +37,24 @@
             <groupId>io.github.openfeign</groupId>
             <artifactId>feign-okhttp</artifactId>
         </dependency>
-
+      
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
         </dependency>
+    
+        <dependency>
+            <groupId>io.github.openfeign.form</groupId>
+            <artifactId>feign-form</artifactId>
+            <version>3.8.0</version>
+        </dependency>
 
+        <dependency>
+            <groupId>io.github.openfeign.form</groupId>
+            <artifactId>feign-form-spring</artifactId>
+            <version>3.8.0</version>
+        </dependency>
+	    
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>

spring-cloud/spring-cloud-openfeign/src/main/java/com/baeldung/cloud/openfeign/fileupload/config/FeignSupportConfig.java

@@ -0,0 +1,22 @@
+package com.baeldung.cloud.openfeign.fileupload.config;
+
+import org.springframework.beans.factory.ObjectFactory;
+import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
+import org.springframework.cloud.openfeign.support.SpringEncoder;
+import org.springframework.context.annotation.Bean;
+import org.springframework.web.client.RestTemplate;
+
+import feign.codec.Encoder;
+import feign.form.spring.SpringFormEncoder;
+
+public class FeignSupportConfig {
+    @Bean
+    public Encoder multipartFormEncoder() {
+        return new SpringFormEncoder(new SpringEncoder(new ObjectFactory<HttpMessageConverters>() {
+            @Override
+            public HttpMessageConverters getObject() {
+                return new HttpMessageConverters(new RestTemplate().getMessageConverters());
+            }
+        }));
+    }
+}

spring-cloud/spring-cloud-openfeign/src/main/java/com/baeldung/cloud/openfeign/fileupload/controller/FileController.java

@@ -0,0 +1,28 @@
+package com.baeldung.cloud.openfeign.fileupload.controller;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestPart;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.multipart.MultipartFile;
+
+import com.baeldung.cloud.openfeign.fileupload.service.UploadService;
+
+@RestController
+public class FileController {
+    
+    @Autowired
+    private UploadService service;
+    
+    @PostMapping(value = "/upload")
+    public String handleFileUpload(@RequestPart(value = "file") MultipartFile file) {
+        return service.uploadFile(file);
+    }
+    
+    @PostMapping(value = "/upload-mannual-client")
+    public boolean handleFileUploadWithManualClient(
+            @RequestPart(value = "file") MultipartFile file) {
+        return service.uploadFileWithManualClient(file);
+    }
+    
+}

spring-cloud/spring-cloud-openfeign/src/main/java/com/baeldung/cloud/openfeign/fileupload/service/UploadClient.java

@@ -0,0 +1,15 @@
+package com.baeldung.cloud.openfeign.fileupload.service;
+
+import org.springframework.cloud.openfeign.FeignClient;
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestPart;
+import org.springframework.web.multipart.MultipartFile;
+
+import com.baeldung.cloud.openfeign.fileupload.config.FeignSupportConfig;
+
+@FeignClient(name = "file", url = "http://localhost:8081", configuration = FeignSupportConfig.class)
+public interface UploadClient {
+    @PostMapping(value = "/upload-file", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
+    String fileUpload(@RequestPart(value = "file") MultipartFile file);
+}

spring-cloud/spring-cloud-openfeign/src/main/java/com/baeldung/cloud/openfeign/fileupload/service/UploadResource.java

@@ -0,0 +1,16 @@
+package com.baeldung.cloud.openfeign.fileupload.service;
+
+import org.springframework.web.multipart.MultipartFile;
+
+import feign.Headers;
+import feign.Param;
+import feign.RequestLine;
+import feign.Response;
+
+public interface UploadResource {
+    
+    @RequestLine("POST /upload-file")
+    @Headers("Content-Type: multipart/form-data")
+    Response uploadFile(@Param("file") MultipartFile file);
+    
+}

spring-cloud/spring-cloud-openfeign/src/main/java/com/baeldung/cloud/openfeign/fileupload/service/UploadService.java

@@ -0,0 +1,29 @@
+package com.baeldung.cloud.openfeign.fileupload.service;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+import org.springframework.web.multipart.MultipartFile;
+
+import feign.Feign;
+import feign.Response;
+import feign.form.spring.SpringFormEncoder;
+
+@Service
+public class UploadService {
+    private static final String HTTP_FILE_UPLOAD_URL = "http://localhost:8081";
+    
+    @Autowired
+    private UploadClient client;
+    
+    public boolean uploadFileWithManualClient(MultipartFile file) {
+        UploadResource fileUploadResource = Feign.builder().encoder(new SpringFormEncoder())
+                .target(UploadResource.class, HTTP_FILE_UPLOAD_URL);
+        Response response = fileUploadResource.uploadFile(file);
+        return response.status() == 200;
+    }
+    
+    public String uploadFile(MultipartFile file) {
+        return client.fileUpload(file);
+    }
+    
+}

spring-cloud/spring-cloud-openfeign/src/test/java/com/baeldung/cloud/openfeign/OpenFeignFileUploadLiveTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.cloud.openfeign;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+
+import org.apache.commons.io.IOUtils;
+import org.junit.Assert;
+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.mock.web.MockMultipartFile;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.web.multipart.MultipartFile;
+
+import com.baeldung.cloud.openfeign.fileupload.service.UploadService;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class OpenFeignFileUploadLiveTest {
+    
+    @Autowired
+    private UploadService uploadService;
+    
+    private static String FILE_NAME = "fileupload.txt";
+    
+    @Test
+    public void whenFeignBuilder_thenFileUploadSuccess() throws IOException {
+        ClassLoader classloader = Thread.currentThread().getContextClassLoader();
+        File file = new File(classloader.getResource(FILE_NAME).getFile());
+        Assert.assertTrue(file.exists());
+        FileInputStream input = new FileInputStream(file);
+        MultipartFile multipartFile = new MockMultipartFile("file", file.getName(), "text/plain",
+                IOUtils.toByteArray(input));
+        Assert.assertTrue(uploadService.uploadFileWithManualClient(multipartFile));
+    }
+    
+    @Test
+    public void whenAnnotatedFeignClient_thenFileUploadSuccess() throws IOException {
+        ClassLoader classloader = Thread.currentThread().getContextClassLoader();
+        File file = new File(classloader.getResource(FILE_NAME).getFile());
+        Assert.assertTrue(file.exists());
+        FileInputStream input = new FileInputStream(file);
+        MultipartFile multipartFile = new MockMultipartFile("file", file.getName(), "text/plain",
+                IOUtils.toByteArray(input));
+        String uploadFile = uploadService.uploadFile(multipartFile);
+        Assert.assertNotNull(uploadFile);
+    }
+}