Merge remote-tracking branch 'upstream/master' into feature/BAEL-6695-BooleanValidation

apache-kafka-2/README.md

@@ -13,3 +13,4 @@ You can build the project from the command line using: *mvn clean install*, or i
 - [Read Data From the Beginning Using Kafka Consumer API](https://www.baeldung.com/java-kafka-consumer-api-read)
 - [Get Partition Count for a Topic in Kafka](https://www.baeldung.com/java-kafka-partition-count-topic)
 - [bootstrap-server in Kafka Configuration](https://www.baeldung.com/java-kafka-bootstrap-server)
+- [Introduction to Apache Kafka](https://www.baeldung.com/apache-kafka)

apache-kafka-2/src/test/java/com/baeldung/kafka/multipletopics/MultipleTopicsLiveTest.java

@@ -0,0 +1,103 @@
+package com.baeldung.kafka.multipletopics;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.Properties;
+import java.util.concurrent.ExecutionException;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.serialization.StringDeserializer;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.containers.KafkaContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+// This live test needs a Docker Daemon running so that a kafka container can be created
+
+@Testcontainers
+public class MultipleTopicsLiveTest {
+
+    private final Logger log = LoggerFactory.getLogger(MultipleTopicsLiveTest.class);
+
+    private static final String CARD_PAYMENTS_TOPIC = "card-payments";
+    private static final String BANK_TRANSFERS_TOPIC = "bank-transfers";
+    private static KafkaProducer<String, String> producer;
+    private static KafkaConsumer<String, String> consumer;
+
+    @Container
+    private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
+
+    @BeforeAll
+    static void setup() {
+        KAFKA_CONTAINER.addExposedPort(9092);
+        producer = new KafkaProducer<>(getProducerProperties());
+        consumer = new KafkaConsumer<>(getConsumerProperties());
+    }
+
+    @AfterAll
+    static void destroy() {
+        KAFKA_CONTAINER.stop();
+    }
+
+    private static Properties getProducerProperties() {
+        Properties producerProperties = new Properties();
+        producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        return producerProperties;
+    }
+
+    private static Properties getConsumerProperties() {
+        Properties consumerProperties = new Properties();
+        consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
+        consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+        consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, "payments");
+        return consumerProperties;
+    }
+
+    @Test
+    void whenSendingMessagesOnTwoTopics_thenConsumerReceivesMessages() throws Exception {
+        publishMessages();
+
+        consumer.subscribe(Arrays.asList(CARD_PAYMENTS_TOPIC, BANK_TRANSFERS_TOPIC));
+
+        int eventsProcessed = 0;
+        for (ConsumerRecord<String, String> record : consumer.poll(Duration.ofSeconds(10))) {
+            log.info("Event on topic={}, payload={}", record.topic(), record.value());
+            eventsProcessed++;
+        }
+
+        assertThat(eventsProcessed).isEqualTo(2);
+    }
+
+    private void publishMessages() throws ExecutionException, InterruptedException {
+        ProducerRecord<String, String> cardPayment = new ProducerRecord<>(CARD_PAYMENTS_TOPIC, createCardPayment());
+        producer.send(cardPayment).get();
+
+        ProducerRecord<String, String> bankTransfer = new ProducerRecord<>(BANK_TRANSFERS_TOPIC, createBankTransfer());
+        producer.send(bankTransfer).get();
+    }
+
+    private String createCardPayment() {
+        return "{\"paymentReference\":\"A184028KM0013790\", \"type\":\"card\", \"amount\":\"275\", \"currency\":\"GBP\"}";
+    }
+
+    private String createBankTransfer() {
+        return "{\"paymentReference\":\"19ae2-18mk73-009\", \"type\":\"bank\", \"amount\":\"150\", \"currency\":\"EUR\"}";
+    }
+}

core-java-modules/core-java-21/README.md

@@ -1,3 +1,5 @@
 ## Relevant Articles
 - [Sequenced Collections in Java 21](https://www.baeldung.com/java-21-sequenced-collections)
 - [String Templates in Java 21](https://www.baeldung.com/java-21-string-templates)
+- [Unnamed Classes and Instance Main Methods in Java 21](https://www.baeldung.com/java-21-unnamed-class-instance-main)
+- [Unnamed Patterns and Variables in Java 21](https://www.baeldung.com/java-unnamed-patterns-variables)

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

@@ -5,3 +5,4 @@ This module contains articles about Java Character Class
 ### Relevant Articles: 
 - [Character#isAlphabetic vs. Character#isLetter](https://www.baeldung.com/java-character-isletter-isalphabetic)
 - [Difference Between Java’s “char” and “String”](https://www.baeldung.com/java-char-vs-string)
+- [Increment Character in Java](https://www.baeldung.com/java-char-sequence)

core-java-modules/core-java-collections-5/README.md

@@ -5,4 +5,6 @@
 ### Relevant Articles:
 - [Introduction to Roaring Bitmap](https://www.baeldung.com/java-roaring-bitmap-intro)
 - [Creating Custom Iterator in Java](https://www.baeldung.com/java-creating-custom-iterator)
+- [Difference Between Arrays.sort() and Collections.sort()](https://www.baeldung.com/java-arrays-collections-sort-methods)
+- [Skipping the First Iteration in Java](https://www.baeldung.com/java-skip-first-iteration)
 - More articles: [[<-- prev]](/core-java-modules/core-java-collections-4)

core-java-modules/core-java-collections-array-list-2/README.md

@@ -3,4 +3,4 @@
 This module contains articles about the Java ArrayList collection
 
 ### Relevant Articles:
-- [Create an ArrayList with Multiple Object Types](https://www.baeldung.com/arraylist-with-multiple-object-types)
+- [Create an ArrayList with Multiple Object Types](https://www.baeldung.com/java-arraylist-multiple-object-types)

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

@@ -3,3 +3,4 @@
 This module contains articles about conversions among Collection types in Java.
 
 ### Relevant Articles:
+- [Converting HashMap Values to an ArrayList in Java](https://www.baeldung.com/java-hashmap-arraylist)

core-java-modules/core-java-collections-maps-7/README.md

@@ -0,0 +1 @@
+## Relevant Articles

core-java-modules/core-java-collections-maps-7/pom.xml

@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-collections-maps-7</artifactId>
+    <name>core-java-collections-maps-7</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <artifactId>core-java-modules</artifactId>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <properties>
+        <spring.version>5.2.5.RELEASE</spring.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>2.12.4</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>1.36</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <version>2.8.9</version>
+        </dependency>
+        <dependency>
+            <groupId>org.json</groupId>
+            <artifactId>json</artifactId>
+            <version>20230227</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.8.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.8.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.8.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.1</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

core-java-modules/core-java-collections-maps-7/src/main/java/com/baeldung/map/ConvertHashMapStringToHashMapObjectUsingtoString.java

@@ -0,0 +1,60 @@
+package com.baeldung.map;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ConvertHashMapStringToHashMapObjectUsingtoString {
+    public String name;
+    public int age;
+
+    public ConvertHashMapStringToHashMapObjectUsingtoString(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public static ConvertHashMapStringToHashMapObjectUsingtoString deserializeCustomObject(String valueString) {
+        if (valueString.startsWith("{") && valueString.endsWith("}")) {
+            valueString = valueString.substring(1, valueString.length() - 1);
+            String[] parts = valueString.split(",");
+            String name = null;
+            int age = -1;
+            for (String part : parts) {
+                String[] keyValue = part.split("=");
+                if (keyValue.length == 2) {
+                    String key = keyValue[0].trim();
+                    String val = keyValue[1].trim();
+                    if (key.equals("name")) {
+                        name = val;
+                    } else if (key.equals("age")) {
+                        age = Integer.parseInt(val);
+                    }
+                }
+            }
+            if (name != null && age >= 0) {
+                return new ConvertHashMapStringToHashMapObjectUsingtoString(name, age);
+            }
+        }
+        return new ConvertHashMapStringToHashMapObjectUsingtoString("", -1);
+    }
+
+    public static void main(String[] args) {
+        String hashMapString = "{key1={name=John, age=30}, key2={name=Alice, age=25}}";
+        String keyValuePairs = hashMapString.replaceAll("[{}\\s]", "");
+        String[] pairs = keyValuePairs.split(",");
+        Map<String, ConvertHashMapStringToHashMapObjectUsingtoString> actualHashMap = new HashMap<>();
+        for (String pair : pairs) {
+            String[] keyValue = pair.split("=");
+            if (keyValue.length == 2) {
+                String key = keyValue[0];
+                ConvertHashMapStringToHashMapObjectUsingtoString value = deserializeCustomObject(keyValue[1]);
+                actualHashMap.put(key, value);
+            }
+        }
+        System.out.println(actualHashMap);
+    }
+
+    @Override
+    public String toString() {
+        return "{name=" + name + ", age=" + age + "}";
+    }
+}

core-java-modules/core-java-collections-maps-7/src/test/java/com/baeldung/map/ConvertHashMapStringToHashMapObjectUsingtoStringUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.map;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class ConvertHashMapStringToHashMapObjectUsingtoStringUnitTest {
+
+    @Test
+    void givenValidCustomObject_whenSerializing_thenSerializedStringIsCorrect() {
+        ConvertHashMapStringToHashMapObjectUsingtoString customObject = new ConvertHashMapStringToHashMapObjectUsingtoString("John", 30);
+        String expectedSerializedString = "{name=John, age=30}";
+        assertEquals(expectedSerializedString, customObject.toString());
+    }
+
+    @Test
+    void givenValidSerializedString_whenDeserializing_thenCustomObjectIsCorrect() {
+        String serializedString = "{name=Alice, age=25}";
+        ConvertHashMapStringToHashMapObjectUsingtoString customObject = ConvertHashMapStringToHashMapObjectUsingtoString.deserializeCustomObject(serializedString);
+        assertEquals("Alice", customObject.name);
+        assertEquals(25, customObject.age);
+    }
+
+    @Test
+    void givenInvalidSerializedString_whenDeserializing_thenDefaultCustomObjectIsCreated() {
+        String invalidSerializedString = "{invalidString}";
+        ConvertHashMapStringToHashMapObjectUsingtoString customObject = ConvertHashMapStringToHashMapObjectUsingtoString.deserializeCustomObject(invalidSerializedString);
+        assertEquals("", customObject.name);
+        assertEquals(-1, customObject.age);
+    }
+}

core-java-modules/core-java-datetime-conversion/src/test/java/com/baeldung/epochtolocaldate/EpochTimeToLocalDateTimeConverterUnitTest.java

@@ -12,10 +12,10 @@ public class EpochTimeToLocalDateTimeConverterUnitTest {
     @Test
     public void testConvertEpochTimeToLocalDateTime() {
         long epochTimeMillis = 1624962431000L; // Example epoch time in milliseconds
-        LocalDateTime expectedDateTime = LocalDateTime.of(2021, 6, 29, 12, 13, 51);
+        LocalDateTime expectedDateTime = LocalDateTime.of(2021, 6, 29, 10, 27, 11);
 
         Instant instant = Instant.ofEpochMilli(epochTimeMillis);
-        ZoneId zoneId = ZoneId.systemDefault();
+        ZoneId zoneId = ZoneId.of("UTC");
         LocalDateTime actualDateTime = instant.atZone(zoneId).toLocalDateTime();
 
         assertEquals(expectedDateTime, actualDateTime);

core-java-modules/core-java-io-5/README.md

@@ -3,6 +3,6 @@
 This module contains articles about core Java input and output (IO)
 
 ### Relevant Articles: 
-
+- [Get File Extension From MIME Type in Java](https://www.baeldung.com/java-mime-type-file-extension)
 - [[<-- Prev]](/core-java-modules/core-java-io-4)
 

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

@@ -14,5 +14,6 @@ This module contains articles about working with the operating system (OS) in Ja
 - [How to Run a Shell Command in Java](http://www.baeldung.com/run-shell-command-in-java)
 - [Taking Screenshots Using Java](https://www.baeldung.com/java-taking-screenshots)
 - [Java Sound API – Capturing Microphone](https://www.baeldung.com/java-sound-api-capture-mic)
+- [How to Detect the Username Using Java](https://www.baeldung.com/java-get-username)
 
 This module uses Java 9, so make sure to have the JDK 9 installed to run it.

core-java-modules/core-java-regex-2/README.md

@@ -9,4 +9,5 @@
 - [Regular Expression: \z vs \Z Anchors in Java](https://www.baeldung.com/java-regular-expression-z-vs-z-anchors)
 - [Extract Text Between Square Brackets](https://www.baeldung.com/java-get-content-between-square-brackets)
 - [Get the Indexes of Regex Pattern Matches in Java](https://www.baeldung.com/java-indexes-regex-pattern-matches)
+- [Check if a String is Strictly Alphanumeric With Java](https://www.baeldung.com/java-check-string-contains-only-letters-numbers)
 - More articles: [[<-- prev]](/core-java-modules/core-java-regex)

core-java-modules/core-java-streams-5/pom.xml

@@ -43,6 +43,11 @@
             <artifactId>vavr</artifactId>
             <version>${vavr.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -72,6 +77,7 @@
         <maven.compiler.source>12</maven.compiler.source>
         <maven.compiler.target>12</maven.compiler.target>
         <vavr.version>0.10.2</vavr.version>
+        <guava.version>32.1.2-jre</guava.version>
     </properties>
 
 </project>

core-java-modules/core-java-streams-5/src/main/java/com/baeldung/streams/partitioning/PartitionStream.java

@@ -0,0 +1,90 @@
+package com.baeldung.streams.partitioning;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collector;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+import com.google.common.collect.Iterables;
+
+public class PartitionStream {
+
+    public static <T> Stream<List<T>> partitionList(List<T> source, int batchSize) {
+        if (batchSize <= 0) {
+            throw new IllegalArgumentException(String.format("Expected the batchSize to be greater than ZERO, actual value was: %s", batchSize));
+        }
+        if (source.isEmpty()) {
+            return Stream.empty();
+        }
+        int nrOfFullBatches = (source.size() - 1) / batchSize;
+        return IntStream.rangeClosed(0, nrOfFullBatches)
+          .mapToObj(batch -> {
+              int startIndex = batch * batchSize;
+              int endIndex = (batch == nrOfFullBatches) ? source.size() : (batch + 1) * batchSize;
+              return source.subList(startIndex, endIndex);
+          });
+    }
+
+    public static <T> Iterable<List<T>> partitionUsingGuava(Stream<T> source, int batchSize) {
+        return Iterables.partition(source::iterator, batchSize);
+    }
+
+    public static <T> List<List<T>> partitionStream(Stream<T> source, int batchSize) {
+        return source.collect(partitionBySize(batchSize, Collectors.toList()));
+    }
+
+    public static <T, A, R> Collector<T, ?, R> partitionBySize(int batchSize, Collector<List<T>, A, R> downstream) {
+        Supplier<Accumulator<T, A>> supplier = () -> new Accumulator<>(
+          batchSize,
+          downstream.supplier().get(),
+          downstream.accumulator()::accept
+        );
+
+        BiConsumer<Accumulator<T, A>, T> accumulator = (acc, value) -> acc.add(value);
+
+        BinaryOperator<Accumulator<T, A>> combiner = (acc1, acc2) -> acc1.combine(acc2, downstream.combiner());
+
+        Function<Accumulator<T, A>, R> finisher = acc -> {
+            if (!acc.values.isEmpty()) {
+                downstream.accumulator().accept(acc.downstreamAccumulator, acc.values);
+            }
+            return downstream.finisher().apply(acc.downstreamAccumulator);
+        };
+
+        return Collector.of(supplier, accumulator, combiner, finisher, Collector.Characteristics.UNORDERED);
+    }
+
+    static class Accumulator<T, A> {
+        private final List<T> values = new ArrayList<>();
+        private final int batchSize;
+        private A downstreamAccumulator;
+        private final BiConsumer<A, List<T>> batchFullListener;
+
+        Accumulator(int batchSize, A accumulator, BiConsumer<A, List<T>> onBatchFull) {
+            this.batchSize = batchSize;
+            this.downstreamAccumulator = accumulator;
+            this.batchFullListener = onBatchFull;
+        }
+
+        void add(T value) {
+            values.add(value);
+            if (values.size() == batchSize) {
+                batchFullListener.accept(downstreamAccumulator, new ArrayList<>(values));
+                values.clear();
+            }
+        }
+
+        Accumulator<T, A> combine(Accumulator<T, A> other, BinaryOperator<A> accumulatorCombiner) {
+            this.downstreamAccumulator = accumulatorCombiner.apply(downstreamAccumulator, other.downstreamAccumulator);
+            other.values.forEach(this::add);
+            return this;
+        }
+    }
+
+}

core-java-modules/core-java-streams-5/src/test/java/com/baeldung/partitioning/PartitionStreamsUnitTest.java

@@ -0,0 +1,82 @@
+package com.baeldung.partitioning;
+
+import static com.baeldung.streams.partitioning.PartitionStream.partitionList;
+import static com.baeldung.streams.partitioning.PartitionStream.partitionStream;
+import static com.baeldung.streams.partitioning.PartitionStream.partitionUsingGuava;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.assertj.core.api.Assertions.atIndex;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.Test;
+
+public class PartitionStreamsUnitTest {
+
+    @Test
+    void whenPartitionList_thenReturnThreeSubLists() {
+        List<Integer> source = List.of(1, 2, 3, 4, 5, 6, 7, 8);
+
+        Stream<List<Integer>> result = partitionList(source, 3);
+
+        assertThat(result)
+          .containsExactlyInAnyOrder(
+            List.of(1, 2, 3),
+            List.of(4, 5, 6),
+            List.of(7, 8)
+          );
+    }
+
+    @Test
+    void whenPartitionEmptyList_thenReturnEmptyStream() {
+        Stream<List<Integer>> result = partitionList(Collections.emptyList(), 3);
+
+        assertThat(result).isEmpty();
+    }
+
+    @Test
+    void whenPartitionListWithNegativeBatchSize_thenThrowException() {
+        assertThatThrownBy(() -> partitionList(List.of(1,2,3), -1))
+          .isInstanceOf(IllegalArgumentException.class)
+          .hasMessage("Expected the batchSize to be greater than ZERO, actual value was: -1");
+    }
+
+    @Test
+    void whenPartitionParallelStream_thenReturnThreeSubLists() {
+        Stream<Integer> source = Stream.of(1, 2, 3, 4, 5, 6, 7, 8).parallel();
+
+        List<List<Integer>> result = partitionStream(source, 3);
+
+        assertThat(result)
+          .hasSize(3)
+          .satisfies(batch -> assertThat(batch).hasSize(3), atIndex(0))
+          .satisfies(batch -> assertThat(batch).hasSize(3), atIndex(1))
+          .satisfies(batch -> assertThat(batch).hasSize(2), atIndex(2));
+    }
+
+    @Test
+    void whenPartitionEmptyParallelStream_thenReturnEmptyList() {
+        Stream<Integer> source = Stream.<Integer>empty().parallel();
+
+        List<List<Integer>> result = partitionStream(source, 3);
+
+        assertThat(result).isEmpty();
+    }
+
+    @Test
+    void whenPartitionParallelStreamWithGuava_thenReturnThreeSubLists() {
+        Stream<Integer> source = Stream.of(1, 2, 3, 4, 5, 6, 7, 8).parallel();
+
+        Iterable<List<Integer>> result = partitionUsingGuava(source, 3);
+
+        assertThat(result)
+          .map(ArrayList::new)
+          .hasSize(3)
+          .satisfies(batch -> assertThat(batch).asList().hasSize(3), atIndex(0))
+          .satisfies(batch -> assertThat(batch).asList().hasSize(3), atIndex(1))
+          .satisfies(batch -> assertThat(batch).asList().hasSize(2), atIndex(2));
+    }
+}

libraries-apache-commons-2/pom.xml

@@ -28,12 +28,18 @@
             <artifactId>commons-vfs2</artifactId>
             <version>${commons-vfs2.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-text</artifactId>
+            <version>${apache-commons-text.version}</version>
+        </dependency>
     </dependencies>
 
     <properties>
         <commons-compress.version>1.23.0</commons-compress.version>
         <ant.version>1.10.13</ant.version>
         <commons-vfs2.version>2.9.0</commons-vfs2.version>
+        <apache-commons-text.version>1.10.0</apache-commons-text.version>
     </properties>
 
 </project>

libraries-apache-commons-2/src/main/java/com/baeldung/commons/convertunicode/UnicodeConverterUtil.java

@@ -0,0 +1,29 @@
+package com.baeldung.commons.convertunicode;
+
+import org.apache.commons.text.StringEscapeUtils;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class UnicodeConverterUtil {
+
+    public static String decodeWithApacheCommons(String input) {
+        return StringEscapeUtils.unescapeJava(input);
+    }
+
+    public static String decodeWithPlainJava(String input) {
+        Pattern pattern = Pattern.compile("\\\\u[0-9a-fA-F]{4}");
+        Matcher matcher = pattern.matcher(input);
+
+        StringBuilder decodedString = new StringBuilder();
+
+        while (matcher.find()) {
+            String unicodeSequence = matcher.group();
+            char unicodeChar = (char) Integer.parseInt(unicodeSequence.substring(2), 16);
+            matcher.appendReplacement(decodedString, Character.toString(unicodeChar));
+        }
+
+        matcher.appendTail(decodedString);
+        return decodedString.toString();
+    }
+}

libraries-apache-commons-2/src/test/java/com/baeldung/commons/convertunicode/UnicodeConverterUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.commons.convertunicode;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class UnicodeConverterUnitTest {
+
+    @Test
+    public void whenInputHaveUnicodeSequences_ThenDecode() {
+        String encodedString = "\\u0048\\u0065\\u006C\\u006C\\u006F World";
+        String expectedDecodedString = "Hello World";
+        assertEquals(expectedDecodedString, UnicodeConverterUtil.decodeWithApacheCommons(encodedString));
+        assertEquals(expectedDecodedString, UnicodeConverterUtil.decodeWithPlainJava(encodedString));
+    }
+
+    @Test
+    public void whenInputHaveNoUnicodeSequences_ThenDoNothing() {
+        String inputString = "Hello World";
+        assertEquals(inputString, UnicodeConverterUtil.decodeWithApacheCommons(inputString));
+        assertEquals(inputString, UnicodeConverterUtil.decodeWithPlainJava(inputString));
+    }
+
+    @Test
+    public void whenInputHaveUnicodeSequencesInMiddle_ThenDecode() {
+        String encodedString = "This is a test \\u0069\\u006E the middle.";
+        String expectedDecodedString = "This is a test in the middle.";
+        assertEquals(expectedDecodedString, UnicodeConverterUtil.decodeWithApacheCommons(encodedString));
+        assertEquals(expectedDecodedString, UnicodeConverterUtil.decodeWithPlainJava(encodedString));
+    }
+
+    @Test
+    public void whenInputHaveMultipleUnicodeSequences_ThenDecode() {
+        String encodedString = "Unicode: \\u0048\\u0065\\u006C\\u006C\\u006F \\u0057\\u006F\\u0072\\u006C\\u0064";
+        String expectedDecodedString = "Unicode: Hello World";
+        assertEquals(expectedDecodedString, UnicodeConverterUtil.decodeWithApacheCommons(encodedString));
+        assertEquals(expectedDecodedString, UnicodeConverterUtil.decodeWithPlainJava(encodedString));
+    }
+}

libraries-io/pom.xml

@@ -5,6 +5,18 @@
     <modelVersion>4.0.0</modelVersion>
     <artifactId>libraries-io</artifactId>
     <name>libraries-io</name>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>17</source>
+                    <target>17</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
 
     <parent>
         <groupId>com.baeldung</groupId>
@@ -34,6 +46,11 @@
             <artifactId>zip4j</artifactId>
             <version>${zip4j.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.opencsv</groupId>
+            <artifactId>opencsv</artifactId>
+            <version>${opencsv.version}</version>
+        </dependency>
     </dependencies>
 
     <properties>
@@ -42,6 +59,10 @@
         <sshj.version>0.27.0</sshj.version>
         <vfs.version>2.4</vfs.version>
         <zip4j.version>2.9.0</zip4j.version>
+        <opencsv.version>5.7.1</opencsv.version>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 
 </project>

libraries-io/src/main/java/com/baeldung/java/io/pojotocsv/Application.java

@@ -0,0 +1,4 @@
+package com.baeldung.java.io.pojotocsv;
+
+public record Application(String id, String name, Integer age, String created_at) {
+}

libraries-io/src/main/java/com/baeldung/java/io/pojotocsv/ApplicationWithAnnotation.java

@@ -0,0 +1,8 @@
+package com.baeldung.java.io.pojotocsv;
+
+import com.opencsv.bean.CsvBindByName;
+import com.opencsv.bean.CsvBindByPosition;
+
+public record ApplicationWithAnnotation(@CsvBindByName(column = "id", required = true) @CsvBindByPosition(position = 1) String id, @CsvBindByName(column = "name", required = true) @CsvBindByPosition(position = 0) String name,
+                                        @CsvBindByName(column = "age", required = true) @CsvBindByPosition(position = 2) Integer age, @CsvBindByName(column = "position", required = true) @CsvBindByPosition(position = 3) String created_at) {
+}

libraries-io/src/main/java/com/baeldung/java/io/pojotocsv/BeanToCsv.java

@@ -0,0 +1,55 @@
+package com.baeldung.java.io.pojotocsv;
+
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.List;
+
+import com.opencsv.CSVWriter;
+import com.opencsv.bean.StatefulBeanToCsvBuilder;
+import com.opencsv.exceptions.CsvDataTypeMismatchException;
+import com.opencsv.exceptions.CsvRequiredFieldEmptyException;
+
+public class BeanToCsv {
+
+    public void beanToCSVWithDefault(List<Application> applications) throws Exception {
+        try (FileWriter writer = new FileWriter("src/main/resources/application.csv")) {
+            var builder = new StatefulBeanToCsvBuilder<Application>(writer).withQuotechar(CSVWriter.NO_QUOTE_CHARACTER)
+                .withSeparator(',')
+                .build();
+            builder.write(applications);
+        }
+    }
+
+    public void beanToCSVWithCustomHeaderStrategy(List<Application> applications) throws IOException, CsvRequiredFieldEmptyException, CsvDataTypeMismatchException {
+        try (FileWriter writer = new FileWriter("src/main/resources/application2.csv")) {
+            var mappingStrategy = new CustomHeaderStrategy<Application>();
+            mappingStrategy.setType(Application.class);
+
+            var builder = new StatefulBeanToCsvBuilder<Application>(writer).withQuotechar(CSVWriter.NO_QUOTE_CHARACTER)
+                .withMappingStrategy(mappingStrategy)
+                .build();
+            builder.write(applications);
+        }
+    }
+
+    public void beanToCSVWithCustomPositionStrategy(List<ApplicationWithAnnotation> applications) throws Exception {
+        try (FileWriter writer = new FileWriter("src/main/resources/application3.csv")) {
+            var builder = new StatefulBeanToCsvBuilder<ApplicationWithAnnotation>(writer).withQuotechar(CSVWriter.NO_QUOTE_CHARACTER)
+                .build();
+            builder.write(applications);
+        }
+    }
+
+    public void beanToCSVWithCustomHeaderAndPositionStrategy(List<ApplicationWithAnnotation> applications) throws IOException, CsvRequiredFieldEmptyException, CsvDataTypeMismatchException {
+        try (FileWriter writer = new FileWriter("src/main/resources/application4.csv")) {
+            var mappingStrategy = new CustomColumnPositionStrategy<ApplicationWithAnnotation>();
+            mappingStrategy.setType(ApplicationWithAnnotation.class);
+
+            var builder = new StatefulBeanToCsvBuilder<ApplicationWithAnnotation>(writer).withQuotechar(CSVWriter.NO_QUOTE_CHARACTER)
+                .withMappingStrategy(mappingStrategy)
+                .build();
+            builder.write(applications);
+        }
+    }
+
+}

libraries-io/src/main/java/com/baeldung/java/io/pojotocsv/CustomColumnPositionStrategy.java

@@ -0,0 +1,12 @@
+package com.baeldung.java.io.pojotocsv;
+
+import com.opencsv.bean.ColumnPositionMappingStrategy;
+import com.opencsv.exceptions.CsvRequiredFieldEmptyException;
+
+public class CustomColumnPositionStrategy<T> extends ColumnPositionMappingStrategy<T> {
+    @Override
+    public String[] generateHeader(T bean) throws CsvRequiredFieldEmptyException {
+        super.generateHeader(bean);
+        return super.getColumnMapping();
+    }
+}

libraries-io/src/main/java/com/baeldung/java/io/pojotocsv/CustomHeaderStrategy.java

@@ -0,0 +1,16 @@
+package com.baeldung.java.io.pojotocsv;
+
+import java.util.Arrays;
+
+import com.opencsv.bean.HeaderColumnNameMappingStrategy;
+import com.opencsv.exceptions.CsvRequiredFieldEmptyException;
+
+public class CustomHeaderStrategy<T> extends HeaderColumnNameMappingStrategy<T> {
+    @Override
+    public String[] generateHeader(T bean) throws CsvRequiredFieldEmptyException {
+        String[] header = super.generateHeader(bean);
+        return Arrays.stream(header)
+            .map(String::toLowerCase)
+            .toArray(String[]::new);
+    }
+}

libraries-io/src/main/resources/application.csv

@@ -0,0 +1,4 @@
+AGE,CREATED_AT,ID,NAME
+34,2023-08-11,123,Sam
+44,2023-02-11,456,Tam
+54,2023-03-11,890,Jam

libraries-io/src/main/resources/application2.csv

@@ -0,0 +1,4 @@
+age,created_at,id,name
+34,2023-08-11,123,Sam
+44,2023-02-11,456,Tam
+54,2023-03-11,890,Jam

libraries-io/src/main/resources/application3.csv

@@ -0,0 +1,3 @@
+Sam,123,34,2023-08-11
+Tam,456,44,2023-02-11
+Jam,789,54,2023-03-11

libraries-io/src/main/resources/application4.csv

@@ -0,0 +1,4 @@
+name,id,age,created_at
+Sam,123,34,2023-08-11
+Tam,456,44,2023-02-11
+Jam,789,54,2023-03-11

libraries-io/src/test/java/com/baeldung/java/io/pojotocsv/BeanToCsvUnitTest.java

@@ -0,0 +1,80 @@
+package com.baeldung.java.io.pojotocsv;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+import java.io.BufferedReader;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class BeanToCsvUnitTest {
+
+    List<Application> applications = new ArrayList<>();
+    List<ApplicationWithAnnotation> applicationsWithAnnotation = new ArrayList<>();
+
+    @BeforeEach
+    public void beforeEach() {
+        applications = List.of(new Application("123", "Sam", 34, "2023-08-11"), new Application("456", "Tam", 44, "2023-02-11"), new Application("890", "Jam", 54, "2023-03-11"));
+
+        applicationsWithAnnotation = List.of(new ApplicationWithAnnotation("123", "Sam", 34, "2023-08-11"), new ApplicationWithAnnotation("456", "Tam", 44, "2023-02-11"), new ApplicationWithAnnotation("789", "Jam", 54, "2023-03-11"));
+    }
+
+    @Test
+    public void givenApplicationPOJO_whenUsingDefaultStrategy_thenReceiveCSVFormatWithAscendingOrderOfField() throws Exception {
+        BeanToCsv beanToCsv = new BeanToCsv();
+        beanToCsv.beanToCSVWithDefault(applications);
+        try (BufferedReader bufferedReader = Files.newBufferedReader(Path.of("src/main/resources/application.csv"))) {
+            List<String> content = bufferedReader.lines()
+                .toList();
+            assertThat(content.get(0)).isEqualTo("AGE,CREATED_AT,ID,NAME");
+            assertThat(content.get(1)).isEqualTo("34,2023-08-11,123,Sam");
+            assertThat(content.get(2)).isEqualTo("44,2023-02-11,456,Tam");
+            assertThat(content.get(3)).isEqualTo("54,2023-03-11,890,Jam");
+        }
+    }
+
+    @Test
+    public void givenApplicationPOJO_whenUsingCustomHeaderStrategy_thenReceiveCSVFormatWithCustomHeaders() throws Exception {
+        BeanToCsv beanToCsv = new BeanToCsv();
+        beanToCsv.beanToCSVWithCustomHeaderStrategy(applications);
+        try (BufferedReader bufferedReader = Files.newBufferedReader(Path.of("src/main/resources/application2.csv"))) {
+            List<String> content = bufferedReader.lines()
+                .toList();
+            assertThat(content.get(0)).isEqualTo("age,created_at,id,name");
+            assertThat(content.get(1)).isEqualTo("34,2023-08-11,123,Sam");
+            assertThat(content.get(2)).isEqualTo("44,2023-02-11,456,Tam");
+            assertThat(content.get(3)).isEqualTo("54,2023-03-11,890,Jam");
+        }
+    }
+
+    @Test
+    public void givenApplicationPOJOWithAnnotation_whenUsingCustomPositionStrategy_thenReceiveCSVFormatWithCustomPosition() throws Exception {
+        BeanToCsv beanToCsv = new BeanToCsv();
+        beanToCsv.beanToCSVWithCustomPositionStrategy(applicationsWithAnnotation);
+        try (BufferedReader bufferedReader = Files.newBufferedReader(Path.of("src/main/resources/application3.csv"))) {
+            List<String> content = bufferedReader.lines()
+                .toList();
+            assertThat(content.get(0)).isEqualTo("Sam,123,34,2023-08-11");
+            assertThat(content.get(1)).isEqualTo("Tam,456,44,2023-02-11");
+            assertThat(content.get(2)).isEqualTo("Jam,789,54,2023-03-11");
+        }
+    }
+
+    @Test
+    public void givenApplicationPOJOWithAnnotation_whenUsingCustomHeaderPositionStrategy_thenReceiveCSVFormatWithCustomHeaderPosition() throws Exception {
+        BeanToCsv beanToCsv = new BeanToCsv();
+        beanToCsv.beanToCSVWithCustomHeaderAndPositionStrategy(applicationsWithAnnotation);
+        try (BufferedReader bufferedReader = Files.newBufferedReader(Path.of("src/main/resources/application4.csv"))) {
+            List<String> content = bufferedReader.lines()
+                .toList();
+            assertThat(content.get(0)).isEqualTo("name,id,age,created_at");
+            assertThat(content.get(1)).isEqualTo("Sam,123,34,2023-08-11");
+            assertThat(content.get(2)).isEqualTo("Tam,456,44,2023-02-11");
+            assertThat(content.get(3)).isEqualTo("Jam,789,54,2023-03-11");
+        }
+    }
+}

parent-spring-6/pom.xml

@@ -35,7 +35,7 @@
     </dependencies>
 
     <properties>
-        <spring.version>6.0.10</spring.version>
+        <spring.version>6.0.12</spring.version>
     </properties>
 
 </project>

spring-6-rsocket/README.md

@@ -3,5 +3,5 @@
 This module contains articles about RSocket in Spring Framework 6.
 
 ### Relevant articles
+- [RSocket Interface in Spring 6](https://www.baeldung.com/spring-rsocket)
 
-- [Introduction to RSocket](#)

spring-boot-modules/spring-boot-actuator/pom.xml

@@ -9,9 +9,10 @@
     <description>This is simple boot application for Spring boot actuator test</description>
 
     <parent>
-        <groupId>com.baeldung.spring-boot-modules</groupId>
-        <artifactId>spring-boot-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-3</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-3</relativePath>
     </parent>
 
     <dependencies>
@@ -39,16 +40,6 @@
             <groupId>com.h2database</groupId>
             <artifactId>h2</artifactId>
         </dependency>
-        <dependency>
-            <groupId>javax.servlet</groupId>
-            <artifactId>javax.servlet-api</artifactId>
-            <scope>provided</scope>
-        </dependency>
-        <dependency>
-            <groupId>javax.servlet</groupId>
-            <artifactId>jstl</artifactId>
-            <scope>runtime</scope>
-        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>

spring-boot-modules/spring-boot-actuator/src/main/java/com/baeldung/endpoints/enabling/SecurityConfiguration.java

@@ -1,36 +1,56 @@
 package com.baeldung.endpoints.enabling;
 
 import org.springframework.boot.actuate.autoconfigure.security.servlet.EndpointRequest;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
+import org.springframework.security.config.Customizer;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+
 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
-import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
-import org.springframework.security.crypto.factory.PasswordEncoderFactories;
-import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.security.core.userdetails.User;
+import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.security.provisioning.InMemoryUserDetailsManager;
+import org.springframework.security.web.SecurityFilterChain;
+import org.springframework.security.web.servlet.util.matcher.MvcRequestMatcher;
+import org.springframework.web.servlet.handler.HandlerMappingIntrospector;
 
-@Configuration
 @EnableWebSecurity
-public class SecurityConfiguration extends WebSecurityConfigurerAdapter {
+@Configuration
+public class SecurityConfiguration {
 
-    @Override
-    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
-        PasswordEncoder encoder = PasswordEncoderFactories.createDelegatingPasswordEncoder();
-        auth.inMemoryAuthentication()
-          .withUser("user")
-          .password(encoder.encode("password"))
-          .roles("USER")
-          .and()
-          .withUser("admin")
-          .password(encoder.encode("admin"))
-          .roles("USER", "ADMIN");
+    @Bean
+    MvcRequestMatcher.Builder mvc(HandlerMappingIntrospector introspector) {
+        return new MvcRequestMatcher.Builder(introspector);
     }
 
-    @Override
-    protected void configure(HttpSecurity http) throws Exception {
-        http.requestMatcher(EndpointRequest.toAnyEndpoint())
-          .authorizeRequests((requests) -> requests.anyRequest()
-            .hasRole("ADMIN"));
-        http.httpBasic();
+    @Bean
+    public SecurityFilterChain filterChain(HttpSecurity http, MvcRequestMatcher.Builder mvc) throws Exception {
+        http.httpBasic(Customizer.withDefaults());
+        http.securityMatcher(EndpointRequest.toAnyEndpoint());
+        http.authorizeHttpRequests(authz -> {
+                authz.requestMatchers(mvc.pattern("/actuator/**"))
+                    .hasRole("ADMIN")
+                    .anyRequest()
+                    .authenticated();
+            });
+
+        return http.build();
+    }
+
+
+
+    @Bean
+    public InMemoryUserDetailsManager userDetailsService() {
+        UserDetails user =  User.withDefaultPasswordEncoder()
+            .username("user")
+            .password("password")
+            .roles("USER")
+            .build();
+        UserDetails admin =  User.withDefaultPasswordEncoder()
+            .username("admin")
+            .password("password")
+            .roles("USER", "ADMIN")
+            .build();
+        return new InMemoryUserDetailsManager(user, admin);
     }
 }

spring-boot-modules/spring-boot-actuator/src/main/java/com/baeldung/endpoints/info/User.java

@@ -1,9 +1,9 @@
 package com.baeldung.endpoints.info;
 
-import javax.persistence.Entity;
-import javax.persistence.GeneratedValue;
-import javax.persistence.Id;
-import javax.persistence.Table;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
 
 @Entity
 @Table(name = "users")

spring-boot-modules/spring-boot-actuator/src/main/java/com/baeldung/metrics/MetricsApplication.java

@@ -15,7 +15,7 @@ import org.springframework.context.annotation.ComponentScan;
 import org.springframework.scheduling.annotation.EnableScheduling;
 import org.springframework.web.context.request.RequestContextListener;
 
-import javax.servlet.ServletContext;
+import jakarta.servlet.ServletContext;
 
 @EnableScheduling
 @ComponentScan("com.baeldung.metrics")

spring-boot-modules/spring-boot-actuator/src/main/java/com/baeldung/metrics/filter/MetricFilter.java

@@ -7,14 +7,14 @@ import org.springframework.stereotype.Component;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.support.WebApplicationContextUtils;
 
-import javax.servlet.Filter;
-import javax.servlet.FilterChain;
-import javax.servlet.FilterConfig;
-import javax.servlet.ServletException;
-import javax.servlet.ServletRequest;
-import javax.servlet.ServletResponse;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
+import jakarta.servlet.Filter;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.FilterConfig;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRequest;
+import jakarta.servlet.ServletResponse;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 
 @Component
 public class MetricFilter implements Filter {

spring-boot-modules/spring-boot-actuator/src/test/java/com/baeldung/endpoints/enabling/EndpointEnablingIntegrationTest.java

@@ -13,20 +13,20 @@ import org.springframework.test.web.servlet.MockMvc;
 
 @SpringBootTest
 @AutoConfigureMockMvc
-public class EndpointEnablingIntegrationTest {
+class EndpointEnablingIntegrationTest {
     @Autowired
     private MockMvc mockMvc;
     
     @Test
     @WithMockUser(username = "user", password = "password", roles = "USER")
-    public void givenWrongAuthentication_whenCallingActuator_thenReturns401() throws Exception {
+    void givenWrongAuthentication_whenCallingActuator_thenReturns401() throws Exception {
         mockMvc.perform(get("/actuator"))
           .andExpect(status().isForbidden());
     }
     
     @Test
     @WithMockUser(username = "admin", password = "admin", roles = "ADMIN")
-    public void givenProperAuthentication_whenCallingActuator_thenReturnsExpectedEndpoints() throws Exception {
+    void givenProperAuthentication_whenCallingActuator_thenReturnsExpectedEndpoints() throws Exception {
         mockMvc.perform(get("/actuator"))
           .andExpect(jsonPath("$._links").exists())
           .andExpect(jsonPath("$._links.beans").exists())

spring-boot-modules/spring-boot-graalvm-docker/README.md

@@ -0,0 +1,2 @@
+## Relevant Articles
+- [Create a GraalVM Docker Image](https://www.baeldung.com/java-graalvm-docker-image)

spring-boot-modules/spring-boot-mvc-4/pom.xml

@@ -9,9 +9,10 @@
     <description>Module For Spring Boot MVC Web</description>
 
     <parent>
-        <groupId>com.baeldung.spring-boot-modules</groupId>
-        <artifactId>spring-boot-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-3</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-boot-3</relativePath>
     </parent>
 
     <dependencies>

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/boot/controller/servlet/HelloWorldServlet.java

@@ -4,10 +4,10 @@ import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.Objects;
 
-import javax.servlet.ServletException;
-import javax.servlet.http.HttpServlet;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 
 public class HelloWorldServlet extends HttpServlet {
     private static final long serialVersionUID = 1L;

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/boot/controller/servlet/SpringHelloWorldServlet.java

@@ -4,10 +4,10 @@ import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.Objects;
 
-import javax.servlet.ServletException;
-import javax.servlet.http.HttpServlet;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 
 public class SpringHelloWorldServlet extends HttpServlet {
     private static final long serialVersionUID = 1L;

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/common/error/SpringHelloServletRegistrationBean.java

@@ -2,7 +2,7 @@ package com.baeldung.common.error;
 
 import org.springframework.boot.web.servlet.ServletRegistrationBean;
 
-import javax.servlet.Servlet;
+import jakarta.servlet.Servlet;
 
 public class SpringHelloServletRegistrationBean extends ServletRegistrationBean {
 

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/servlets/configuration/WebAppInitializer.java

@@ -4,9 +4,9 @@ import org.springframework.web.WebApplicationInitializer;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 import org.springframework.web.context.support.XmlWebApplicationContext;
 import org.springframework.web.servlet.DispatcherServlet;
-import javax.servlet.ServletContext;
-import javax.servlet.ServletException;
-import javax.servlet.ServletRegistration;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRegistration;
 
 public class WebAppInitializer implements WebApplicationInitializer {
 

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/servlets/servlets/GenericCustomServlet.java

@@ -1,9 +1,9 @@
 package com.baeldung.servlets.servlets;
 
-import javax.servlet.ServletException;
-import javax.servlet.http.HttpServlet;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import java.io.IOException;
 import java.io.PrintWriter;
 

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/servlets/servlets/javaee/AnnotationServlet.java

@@ -1,10 +1,10 @@
 package com.baeldung.servlets.servlets.javaee;
 
-import javax.servlet.ServletException;
-import javax.servlet.annotation.WebServlet;
-import javax.servlet.http.HttpServlet;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.annotation.WebServlet;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import java.io.IOException;
 
 @WebServlet(name = "AnnotationServlet", description = "Example Servlet Using Annotations", urlPatterns = { "/annotationservlet" })

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/servlets/servlets/javaee/EEWebXmlServlet.java

@@ -1,9 +1,9 @@
 package com.baeldung.servlets.servlets.javaee;
 
-import javax.servlet.ServletException;
-import javax.servlet.http.HttpServlet;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import java.io.IOException;
 import java.io.PrintWriter;
 

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/utils/UtilsApplication.java

@@ -1,6 +1,6 @@
 package com.baeldung.utils;
 
-import javax.annotation.security.RolesAllowed;
+import jakarta.annotation.security.RolesAllowed;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;

spring-boot-modules/spring-boot-mvc-4/src/main/java/com/baeldung/utils/controller/UtilsController.java

@@ -1,6 +1,6 @@
 package com.baeldung.utils.controller;
 
-import javax.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletRequest;
 
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;

spring-boot-modules/spring-boot-mvc-4/src/test/java/com/baeldung/utils/UtilsControllerIntegrationTest.java

@@ -1,32 +1,34 @@
 package com.baeldung.utils;
 
 import com.baeldung.utils.controller.UtilsController;
-import org.junit.Before;
-import org.junit.Test;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 import org.mockito.InjectMocks;
-import org.mockito.MockitoAnnotations;
+
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
 
+import static org.mockito.MockitoAnnotations.openMocks;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
-public class UtilsControllerIntegrationTest {
+class UtilsControllerIntegrationTest {
 
     @InjectMocks
     private UtilsController utilsController;
 
     private MockMvc mockMvc;
 
-    @Before
+    @BeforeEach
     public void setup() {
-        MockitoAnnotations.initMocks(this);
+        openMocks(this);
         this.mockMvc = MockMvcBuilders.standaloneSetup(utilsController).build();
 
     }
 
     @Test
-    public void givenParameter_setRequestParam_andSetSessionAttribute() throws Exception {
+    void givenParameter_setRequestParam_andSetSessionAttribute() throws Exception {
         String param = "testparam";
         this.mockMvc.perform(post("/setParam").param("param", param).sessionAttr("parameter", param)).andExpect(status().isOk());
     }

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/README.md

@@ -0,0 +1,7 @@
+## Spring Cloud Gateway
+
+This module contains articles about Spring Cloud Gateway
+
+### Relevant Articles:
+
+- [Exploring the New Spring Cloud Gateway](http://www.baeldung.com/spring-cloud-gateway)

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/pom.xml

@@ -0,0 +1,54 @@
+<?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>
+    <artifactId>gateway-2</artifactId>
+    <name>gateway-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-boot-2</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../../parent-boot-2</relativePath>
+    </parent>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.junit</groupId>
+                <artifactId>junit-bom</artifactId>
+                <version>${junit-jupiter.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+            <dependency>
+                <groupId>org.springframework.cloud</groupId>
+                <artifactId>spring-cloud-dependencies</artifactId>
+                <version>${spring-cloud-dependencies.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+            <dependency>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-dependencies</artifactId>
+                <version>${spring-boot.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.cloud</groupId>
+            <artifactId>spring-cloud-starter-gateway</artifactId>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <spring-cloud-dependencies.version>2021.0.3</spring-cloud-dependencies.version>
+    </properties>
+
+</project>

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/java/com/baeldung/springcloudgateway/custompredicates/CustomPredicatesApplication.java

@@ -0,0 +1,15 @@
+package com.baeldung.springcloudgateway.custompredicates;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+
+@SpringBootApplication
+public class CustomPredicatesApplication {
+
+    public static void main(String[] args) {
+        new SpringApplicationBuilder(CustomPredicatesApplication.class)
+          .profiles("customroutes")
+          .run(args);
+    }
+
+}

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/java/com/baeldung/springcloudgateway/custompredicates/config/CustomPredicatesConfig.java

@@ -0,0 +1,43 @@
+package com.baeldung.springcloudgateway.custompredicates.config;
+
+import org.springframework.cloud.gateway.route.RouteLocator;
+import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import com.baeldung.springcloudgateway.custompredicates.factories.GoldenCustomerRoutePredicateFactory;
+import com.baeldung.springcloudgateway.custompredicates.factories.GoldenCustomerRoutePredicateFactory.Config;
+import com.baeldung.springcloudgateway.custompredicates.service.GoldenCustomerService;
+
+@Configuration
+public class CustomPredicatesConfig {
+    
+    
+    @Bean
+    public GoldenCustomerRoutePredicateFactory goldenCustomer(GoldenCustomerService goldenCustomerService) {
+        return new GoldenCustomerRoutePredicateFactory(goldenCustomerService);
+    }
+    
+
+    //@Bean
+    public RouteLocator routes(RouteLocatorBuilder builder, GoldenCustomerRoutePredicateFactory gf ) {
+
+        return builder.routes()
+          .route("dsl_golden_route", r -> 
+            r.predicate(gf.apply(new Config(true, "customerId")))
+             .and()
+             .path("/dsl_api/**")
+             .filters(f -> f.stripPrefix(1))
+             .uri("https://httpbin.org")
+          )
+          .route("dsl_common_route", r -> 
+             r.predicate(gf.apply(new Config(false, "customerId")))
+              .and()
+              .path("/dsl_api/**")
+              .filters(f -> f.stripPrefix(1))
+              .uri("https://httpbin.org")
+              )             
+          .build();
+    }
+    
+}

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/java/com/baeldung/springcloudgateway/custompredicates/factories/GoldenCustomerRoutePredicateFactory.java

@@ -0,0 +1,102 @@
+/**
+ * 
+ */
+package com.baeldung.springcloudgateway.custompredicates.factories;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Predicate;
+
+import javax.validation.constraints.NotEmpty;
+
+import org.springframework.cloud.gateway.handler.predicate.AbstractRoutePredicateFactory;
+import org.springframework.http.HttpCookie;
+import org.springframework.validation.annotation.Validated;
+import org.springframework.web.server.ServerWebExchange;
+
+import com.baeldung.springcloudgateway.custompredicates.service.GoldenCustomerService;
+
+/**
+ * @author Philippe
+ *
+ */
+public class GoldenCustomerRoutePredicateFactory extends AbstractRoutePredicateFactory<GoldenCustomerRoutePredicateFactory.Config> {
+
+    private final GoldenCustomerService goldenCustomerService;
+    
+    public GoldenCustomerRoutePredicateFactory(GoldenCustomerService goldenCustomerService ) {
+        super(Config.class);
+        this.goldenCustomerService = goldenCustomerService;
+    }
+
+
+    @Override
+    public List<String> shortcutFieldOrder() {
+        return Arrays.asList("isGolden","customerIdCookie");
+    }
+
+
+    @Override
+    public Predicate<ServerWebExchange> apply(Config config) {
+        
+        return (ServerWebExchange t) -> {
+            List<HttpCookie> cookies = t.getRequest()
+              .getCookies()
+              .get(config.getCustomerIdCookie());
+              
+            boolean isGolden; 
+            if ( cookies == null || cookies.isEmpty()) {
+                isGolden = false;
+            }
+            else {                
+                String customerId = cookies.get(0).getValue();                
+                isGolden = goldenCustomerService.isGoldenCustomer(customerId);
+            }
+              
+            return config.isGolden()?isGolden:!isGolden;           
+        };
+    }
+    
+    
+    @Validated
+    public static class Config {        
+        boolean isGolden = true;
+        
+        @NotEmpty
+        String customerIdCookie = "customerId";
+        
+        
+        public Config() {}
+        
+        public Config( boolean isGolden, String customerIdCookie) {
+            this.isGolden = isGolden;
+            this.customerIdCookie = customerIdCookie;
+        }
+        
+        public boolean isGolden() {
+            return isGolden;
+        }
+        
+        public void setGolden(boolean value) {
+            this.isGolden = value;
+        }
+
+        /**
+         * @return the customerIdCookie
+         */
+        public String getCustomerIdCookie() {
+            return customerIdCookie;
+        }
+
+        /**
+         * @param customerIdCookie the customerIdCookie to set
+         */
+        public void setCustomerIdCookie(String customerIdCookie) {
+            this.customerIdCookie = customerIdCookie;
+        }
+        
+        
+        
+    }
+    
+}

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/java/com/baeldung/springcloudgateway/custompredicates/service/GoldenCustomerService.java

@@ -0,0 +1,26 @@
+/**
+ * 
+ */
+package com.baeldung.springcloudgateway.custompredicates.service;
+
+import org.springframework.stereotype.Component;
+
+/**
+ * @author Philippe
+ *
+ */
+@Component
+public class GoldenCustomerService {
+    
+    public boolean isGoldenCustomer(String customerId) {
+        
+        // TODO: Add some AI logic to check is this customer deserves a "golden" status ;^)
+        if ( "baeldung".equalsIgnoreCase(customerId)) {
+            return true;
+        }
+        else {
+            return false;
+        }
+    }
+
+}

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/java/com/baeldung/springcloudgateway/introduction/IntroductionGatewayApplication.java

@@ -0,0 +1,15 @@
+package com.baeldung.springcloudgateway.introduction;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.PropertySource;
+
+@SpringBootApplication
+@PropertySource("classpath:introduction-application.properties")
+public class IntroductionGatewayApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(IntroductionGatewayApplication.class, args);
+    }
+
+}

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/resources/application-customroutes.yml

@@ -0,0 +1,26 @@
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: golden_route
+        uri: https://httpbin.org
+        predicates:
+        - Path=/api/**
+        - GoldenCustomer=true
+        filters:
+        - StripPrefix=1
+        - AddRequestHeader=GoldenCustomer,true
+      - id: common_route
+        uri: https://httpbin.org
+        predicates:
+        - Path=/api/**
+        - name: GoldenCustomer
+          args:
+            golden: false
+            customerIdCookie: customerId
+        filters:
+        - StripPrefix=1
+        - AddRequestHeader=GoldenCustomer,false
+        
+              
+        

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/resources/application.yml

@@ -0,0 +1,4 @@
+logging:
+  level:
+    org.springframework.cloud.gateway: DEBUG
+    reactor.netty.http.client: DEBUG

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/resources/introduction-application.properties

@@ -0,0 +1,7 @@
+spring.cloud.gateway.routes[0].id=baeldung_route
+spring.cloud.gateway.routes[0].uri=http://www.baeldung.com
+spring.cloud.gateway.routes[0].predicates[0]=Path=/baeldung
+        
+management.endpoints.web.exposure.include=*
+
+server.port=80

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/test/java/com/baeldung/springcloudgateway/custompredicates/CustomPredicatesApplicationLiveTest.java

@@ -0,0 +1,67 @@
+package com.baeldung.springcloudgateway.custompredicates;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.net.URI;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.json.JSONTokener;
+import org.junit.Before;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.web.server.LocalServerPort;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.RequestEntity;
+import org.springframework.http.ResponseEntity;
+import org.springframework.test.context.ActiveProfiles;
+
+/**
+ * This test requires
+ */
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@ActiveProfiles("customroutes")
+public class CustomPredicatesApplicationLiveTest {
+
+    @LocalServerPort
+    String serverPort;
+    
+    @Autowired
+    private TestRestTemplate restTemplate;
+
+    @Test
+    void givenNormalCustomer_whenCallHeadersApi_thenResponseForNormalCustomer() throws JSONException {
+
+        String url = "http://localhost:" + serverPort + "/api/headers";        
+        ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
+        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+        
+        JSONObject json = new JSONObject(response.getBody());
+        JSONObject headers = json.getJSONObject("headers");
+        assertThat(headers.getString("Goldencustomer")).isEqualTo("false");
+        
+    }
+
+    @Test
+    void givenGoldenCustomer_whenCallHeadersApi_thenResponseForGoldenCustomer() throws JSONException {
+
+        String url = "http://localhost:" + serverPort + "/api/headers";   
+        RequestEntity<Void> request = RequestEntity
+            .get(URI.create(url))
+            .header("Cookie", "customerId=baeldung")
+            .build();
+            
+        ResponseEntity<String> response = restTemplate.exchange(request, String.class);
+        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
+        
+        JSONObject json = new JSONObject(response.getBody());
+        JSONObject headers = json.getJSONObject("headers");
+        assertThat(headers.getString("Goldencustomer")).isEqualTo("true");
+        
+    }
+    
+}

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/test/java/com/baeldung/springcloudgateway/introduction/LoggerListAppender.java

@@ -0,0 +1,25 @@
+package com.baeldung.springcloudgateway.introduction;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.AppenderBase;
+
+public class LoggerListAppender extends AppenderBase<ILoggingEvent> {
+
+    static private List<ILoggingEvent> events = new ArrayList<>();
+
+    @Override
+    protected void append(ILoggingEvent eventObject) {
+        events.add(eventObject);
+    }
+
+    public static List<ILoggingEvent> getEvents() {
+        return events;
+    }
+
+    public static void clearEventList() {
+        events.clear();
+    }
+}

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/test/java/com/baeldung/springcloudgateway/introduction/SpringContextTest.java

@@ -0,0 +1,15 @@
+package com.baeldung.springcloudgateway.introduction;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import com.baeldung.springcloudgateway.introduction.IntroductionGatewayApplication;
+
+
+@SpringBootTest(classes = IntroductionGatewayApplication.class)
+public class SpringContextTest {
+
+    @Test
+    public void whenSpringContextIsBootstrapped_thenNoExceptions() {
+    }
+}

spring-cloud-modules/spring-cloud-bootstrap/gateway-2/src/test/resources/logback-test.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="LISTAPPENDER"
+        class="com.baeldung.springcloudgateway.introduction.LoggerListAppender">
+    </appender>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
+        </encoder>
+    </appender>
+    <root level="info">
+        <appender-ref ref="LISTAPPENDER" />
+    </root>
+    <root level="info">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration> 

spring-cloud-modules/spring-cloud-bootstrap/pom.xml

@@ -18,6 +18,7 @@
         <module>config</module>
         <module>discovery</module>
         <module>gateway</module>
+        <module>gateway-2</module>
         <module>svc-book</module>
         <module>svc-rating</module>
         <module>customer-service</module>

spring-kafka-2/src/main/java/com/baeldung/spring/kafka/multipletopics/KafkaConsumerConfig.java

@@ -0,0 +1,36 @@
+package com.baeldung.spring.kafka.multipletopics;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.common.serialization.StringDeserializer;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.kafka.config.ConcurrentKafkaListenerContainerFactory;
+import org.springframework.kafka.core.ConsumerFactory;
+import org.springframework.kafka.core.DefaultKafkaConsumerFactory;
+import org.springframework.kafka.support.serializer.JsonDeserializer;
+
+@Configuration
+public class KafkaConsumerConfig {
+
+    @Value(value = "${spring.kafka.bootstrap-servers}")
+    private String bootstrapServers;
+
+    @Bean
+    public ConsumerFactory<String, PaymentData> consumerFactory() {
+        Map<String, Object> config = new HashMap<>();
+        config.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
+
+        return new DefaultKafkaConsumerFactory<>(config, new StringDeserializer(), new JsonDeserializer<>(PaymentData.class));
+    }
+
+    @Bean
+    public ConcurrentKafkaListenerContainerFactory<String, PaymentData> kafkaListenerContainerFactory() {
+        ConcurrentKafkaListenerContainerFactory<String, PaymentData> factory = new ConcurrentKafkaListenerContainerFactory<>();
+        factory.setConsumerFactory(consumerFactory());
+        return factory;
+    }
+}

spring-kafka-2/src/main/java/com/baeldung/spring/kafka/multipletopics/KafkaMultipleTopicsApplication.java

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

spring-kafka-2/src/main/java/com/baeldung/spring/kafka/multipletopics/KafkaProducerConfig.java

@@ -0,0 +1,34 @@
+package com.baeldung.spring.kafka.multipletopics;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.kafka.core.DefaultKafkaProducerFactory;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.kafka.core.ProducerFactory;
+import org.springframework.kafka.support.serializer.JsonSerializer;
+
+@Configuration
+public class KafkaProducerConfig {
+
+    @Value(value = "${spring.kafka.bootstrap-servers}")
+    private String bootstrapServers;
+
+    @Bean
+    public ProducerFactory<String, PaymentData> producerFactory() {
+        Map<String, Object> config = new HashMap<>();
+        config.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
+
+        return new DefaultKafkaProducerFactory<>(config, new StringSerializer(), new JsonSerializer<>());
+    }
+
+    @Bean
+    public KafkaTemplate<String, PaymentData> kafkaProducer() {
+        return new KafkaTemplate<>(producerFactory());
+    }
+}

spring-kafka-2/src/main/java/com/baeldung/spring/kafka/multipletopics/PaymentData.java

@@ -0,0 +1,54 @@
+package com.baeldung.spring.kafka.multipletopics;
+
+import java.math.BigDecimal;
+import java.util.Currency;
+import java.util.StringJoiner;
+
+public class PaymentData {
+    private String paymentReference;
+    private String type;
+    private BigDecimal amount;
+    private Currency currency;
+
+    public String getPaymentReference() {
+        return paymentReference;
+    }
+
+    public void setPaymentReference(String paymentReference) {
+        this.paymentReference = paymentReference;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    public BigDecimal getAmount() {
+        return amount;
+    }
+
+    public void setAmount(BigDecimal amount) {
+        this.amount = amount;
+    }
+
+    public Currency getCurrency() {
+        return currency;
+    }
+
+    public void setCurrency(Currency currency) {
+        this.currency = currency;
+    }
+
+    @Override
+    public String toString() {
+        return new StringJoiner(", ", PaymentData.class.getSimpleName() + "[", "]")
+          .add("paymentReference='" + paymentReference + "'")
+          .add("type='" + type + "'")
+          .add("amount=" + amount)
+          .add("currency=" + currency)
+          .toString();
+    }
+}

spring-kafka-2/src/main/java/com/baeldung/spring/kafka/multipletopics/PaymentDataListener.java

@@ -0,0 +1,18 @@
+package com.baeldung.spring.kafka.multipletopics;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.kafka.annotation.KafkaListener;
+import org.springframework.kafka.support.KafkaHeaders;
+import org.springframework.messaging.handler.annotation.Header;
+import org.springframework.stereotype.Service;
+
+@Service
+public class PaymentDataListener {
+    private final Logger log = LoggerFactory.getLogger(PaymentDataListener.class);
+
+    @KafkaListener(topics = { "card-payments", "bank-transfers" }, groupId = "payments")
+    public void handlePaymentEvents(PaymentData paymentData, @Header(KafkaHeaders.RECEIVED_TOPIC) String topic) {
+        log.info("Event on topic={}, payload={}", topic, paymentData);
+    }
+}

spring-kafka-2/src/test/java/com/baeldung/spring/kafka/multipletopics/KafkaMultipleTopicsIntegrationTest.java

@@ -0,0 +1,78 @@
+package com.baeldung.spring.kafka.multipletopics;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.doAnswer;
+
+import java.math.BigDecimal;
+import java.util.Currency;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.mock.mockito.SpyBean;
+import org.springframework.kafka.config.KafkaListenerEndpointRegistry;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.kafka.listener.MessageListenerContainer;
+import org.springframework.kafka.test.context.EmbeddedKafka;
+import org.springframework.kafka.test.utils.ContainerTestUtils;
+
+@SpringBootTest(classes = KafkaMultipleTopicsApplication.class)
+@EmbeddedKafka(partitions = 1, brokerProperties = { "listeners=PLAINTEXT://localhost:9092", "port=9092" })
+public class KafkaMultipleTopicsIntegrationTest {
+    private static final String CARD_PAYMENTS_TOPIC = "card-payments";
+    private static final String BANK_TRANSFERS_TOPIC = "bank-transfers";
+
+    @Autowired
+    private KafkaListenerEndpointRegistry kafkaListenerEndpointRegistry;
+
+    @Autowired
+    private KafkaTemplate<String, PaymentData> kafkaProducer;
+
+    @SpyBean
+    private PaymentDataListener paymentsConsumer;
+
+    @BeforeEach
+    void setUp() {
+        // wait for embedded Kafka
+        for (MessageListenerContainer messageListenerContainer : kafkaListenerEndpointRegistry.getListenerContainers()) {
+            ContainerTestUtils.waitForAssignment(messageListenerContainer, 2);
+        }
+    }
+
+    @Test
+    public void whenSendingMessagesOnTwoTopics_thenConsumerReceivesMessages() throws Exception {
+        CountDownLatch countDownLatch = new CountDownLatch(2);
+        doAnswer(invocation -> {
+            countDownLatch.countDown();
+            return null;
+        }).when(paymentsConsumer)
+          .handlePaymentEvents(any(), any());
+
+        kafkaProducer.send(CARD_PAYMENTS_TOPIC, createCardPayment());
+        kafkaProducer.send(BANK_TRANSFERS_TOPIC, createBankTransfer());
+
+        assertThat(countDownLatch.await(5, TimeUnit.SECONDS)).isTrue();
+    }
+
+    private PaymentData createCardPayment() {
+        PaymentData cardPayment = new PaymentData();
+        cardPayment.setAmount(BigDecimal.valueOf(275));
+        cardPayment.setPaymentReference("A184028KM0013790");
+        cardPayment.setCurrency(Currency.getInstance("GBP"));
+        cardPayment.setType("card");
+        return cardPayment;
+    }
+
+    private PaymentData createBankTransfer() {
+        PaymentData bankTransfer = new PaymentData();
+        bankTransfer.setAmount(BigDecimal.valueOf(150));
+        bankTransfer.setPaymentReference("19ae2-18mk73-009");
+        bankTransfer.setCurrency(Currency.getInstance("EUR"));
+        bankTransfer.setType("bank");
+        return bankTransfer;
+    }
+}

testing-modules/junit-5-advanced/README.md

@@ -9,3 +9,4 @@
 - [JUnit – Testing Methods That Call System.exit()](https://www.baeldung.com/junit-system-exit)
 - [Single Assert Call for Multiple Properties in Java Unit Testing](https://www.baeldung.com/java-testing-single-assert-multiple-properties)
 - [Creating a Test Suite With JUnit](https://www.baeldung.com/java-junit-test-suite)
+- [Testing Interface Contract in Java](https://www.baeldung.com/java-junit-verify-interface-contract)