Merge remote-tracking branch 'upstream/master'

core-java-modules/core-java-8-2/README.md

@@ -8,4 +8,5 @@ This module contains articles about Java 8 core features
 - [Java 8 Stream skip() vs limit()](https://www.baeldung.com/java-stream-skip-vs-limit)
 - [Guide to Java BiFunction Interface](https://www.baeldung.com/java-bifunction-interface)
 - [Interface With Default Methods vs Abstract Class](https://www.baeldung.com/java-interface-default-method-vs-abstract-class)
+- [Convert Between Byte Array and UUID in Java](https://www.baeldung.com/java-byte-array-to-uuid)
 - [[<-- Prev]](/core-java-modules/core-java-8)

core-java-modules/core-java-8-2/src/main/java/com/baeldung/game/RockPaperScissorsGame.java

@@ -1,17 +1,24 @@
 package com.baeldung.game;
 
-import java.util.HashMap;
+import java.util.*;
-import java.util.Map;
-import java.util.Random;
-import java.util.Scanner;
 
 class RockPaperScissorsGame {
 
-    private static Map<Integer, String> movesMap = new HashMap<Integer, String>() {{
+    enum Move {
-        put(0, "rock");
+        ROCK("rock"),
-        put(1, "paper");
+        PAPER("paper"),
-        put(2, "scissors");
+        SCISSORS("scissors");
-    }};
+
+        private String value;
+
+        Move(String value) {
+            this.value = value;
+        }
+
+        public String getValue() {
+            return value;
+        }
+    }
 
     public static void main(String[] args) {
         Scanner scanner = new Scanner(System.in);
@@ -31,7 +38,7 @@ class RockPaperScissorsGame {
                 break;
             }
 
-            if (!movesMap.containsValue(playerMove)) {
+            if (Arrays.stream(Move.values()).noneMatch(x -> x.getValue().equals(playerMove))) {
                 System.out.println("Your move isn't valid!");
                 continue;
             }
@@ -51,15 +58,15 @@ class RockPaperScissorsGame {
     }
 
     private static boolean isPlayerWin(String playerMove, String computerMove) {
-        return playerMove.equals("rock") && computerMove.equals("scissors")
+        return playerMove.equals(Move.ROCK.value) && computerMove.equals(Move.SCISSORS.value)
-                || (playerMove.equals("scissors") && computerMove.equals("paper"))
+                || (playerMove.equals(Move.SCISSORS.value) && computerMove.equals(Move.PAPER.value))
-                || (playerMove.equals("paper") && computerMove.equals("rock"));
+                || (playerMove.equals(Move.PAPER.value) && computerMove.equals(Move.ROCK.value));
     }
 
     private static String getComputerMove() {
         Random random = new Random();
         int randomNumber = random.nextInt(3);
-        String computerMove = movesMap.get(randomNumber);
+        String computerMove = Move.values()[randomNumber].getValue();
         System.out.println("Computer move: " + computerMove);
         return computerMove;
     }

core-java-modules/core-java-collections-4/README.md

@@ -7,3 +7,4 @@
 - [ArrayList vs. LinkedList vs. HashMap in Java](https://www.baeldung.com/java-arraylist-vs-linkedlist-vs-hashmap)
 - [Java Deque vs. Stack](https://www.baeldung.com/java-deque-vs-stack)
 - [Collection.toArray(new T[0]) or .toArray(new T[size])](https://www.baeldung.com/java-collection-toarray-methods)
+- [Create an Empty Map in Java](https://www.baeldung.com/java-create-empty-map)

core-java-modules/core-java-collections-4/src/main/java/com/baeldung/maps/initialize/EmptyMapInitializer.java

@@ -0,0 +1,56 @@
+package com.baeldung.maps.initialize;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Maps;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.NavigableMap;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+public class EmptyMapInitializer {
+
+  public static Map<String, String> articleMap;
+  static {
+    articleMap = new HashMap<>();
+  }
+
+  public static Map<String, String> createEmptyMap() {
+    return Collections.emptyMap();
+  }
+
+  public void createMapUsingConstructors() {
+    Map hashMap = new HashMap();
+    Map linkedHashMap = new LinkedHashMap();
+    Map treeMap = new TreeMap();
+  }
+
+  public Map<String, String> createEmptyMapUsingMapsObject() {
+    Map<String, String> emptyMap = Maps.newHashMap();
+    return emptyMap;
+  }
+
+  public Map createGenericEmptyMapUsingMapsObject() {
+    Map genericEmptyMap = Maps.<String, Integer>newHashMap();
+    return genericEmptyMap;
+  }
+
+  public static Map<String, String> createMapUsingGuava() {
+    Map<String, String> emptyMapUsingGuava =
+        Maps.newHashMap(ImmutableMap.of());
+    return emptyMapUsingGuava;
+  }
+
+  public SortedMap<String, String> createEmptySortedMap() {
+    SortedMap<String, String> sortedMap = Collections.emptySortedMap();
+    return sortedMap;
+  }
+
+  public NavigableMap<String, String> createEmptyNavigableMap() {
+    NavigableMap<String, String> navigableMap = Collections.emptyNavigableMap();
+    return navigableMap;
+  }
+
+}

core-java-modules/core-java-collections-4/src/test/java/com/baeldung/maps/initialize/EmptyMapInitializerUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.maps.initialize;
+
+import java.util.Map;
+import org.junit.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class EmptyMapInitializerUnitTest {
+
+  @Test(expected=UnsupportedOperationException.class)
+  public void givenEmptyMap_whenAddingEntries_throwsException() {
+    Map<String, String> map = EmptyMapInitializer.createEmptyMap();
+    map.put("key", "value");
+  }
+
+  @Test
+  public void givenEmptyMap_whenChecked_returnsTrue() {
+    assertTrue(EmptyMapInitializer.articleMap.isEmpty());
+  }
+
+  @Test
+  public void givenEmptyMap_whenCreatedUsingGuava_returnsEmptyOrNot() {
+    Map<String, String> emptyMapUsingGuava =
+        EmptyMapInitializer.createMapUsingGuava();
+    assertTrue(emptyMapUsingGuava.isEmpty());
+    emptyMapUsingGuava.put("key", "value");
+    assertFalse(emptyMapUsingGuava.isEmpty());
+  }
+
+}

core-java-modules/core-java-nio-2/src/test/java/com/baeldung/bytebuffer/ByteBufferUnitTest.java

@@ -0,0 +1,339 @@
+package com.baeldung.bytebuffer;
+
+import org.junit.Test;
+
+import java.lang.reflect.Field;
+import java.nio.*;
+import java.nio.charset.StandardCharsets;
+
+import static org.junit.Assert.*;
+
+public class ByteBufferUnitTest {
+    @Test
+    public void givenBufferCreation_whenUsingAllocate_thenSuccess() {
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertNotNull(buffer);
+    }
+
+    @Test
+    public void givenBufferCreation_whenUsingAllocateDirect_thenSuccess() {
+        ByteBuffer buffer = ByteBuffer.allocateDirect(10);
+        assertNotNull(buffer);
+    }
+
+    @Test
+    public void givenBufferCreation_whenUsingWrap_thenSuccess() {
+        byte[] bytes = new byte[10];
+        ByteBuffer buffer = ByteBuffer.wrap(bytes);
+        assertNotNull(buffer);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingAllocate_thenInitialIndices() {
+        // create instance using allocate
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+
+        // get index
+        int position = buffer.position();
+        int limit = buffer.limit();
+        int capacity = buffer.capacity();
+
+        // assert
+        assertEquals(0, position);
+        assertEquals(10, limit);
+        assertEquals(10, capacity);
+    }
+
+    @Test
+    public void givenBufferIndex_whenChangingPositionAndLimit_thenSuccess() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+
+        // change index
+        buffer.position(2);
+        buffer.limit(5);
+
+        // assert
+        assertIndex(buffer, -1, 2, 5, 10);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingWrap_thenInitialIndices() {
+        // create instance
+        byte[] bytes = new byte[10];
+        ByteBuffer buffer = ByteBuffer.wrap(bytes);
+
+        // assert
+        assertIndex(buffer, -1, 0, 10, 10);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingWrapWithOffsetAndLength_thenInitialIndices() {
+        // create instance
+        byte[] bytes = new byte[10];
+        ByteBuffer buffer = ByteBuffer.wrap(bytes, 2, 6);
+
+        // assert
+        assertIndex(buffer, -1, 2, 8, 10);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingMarkAndReset_thenOK() {
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertIndex(buffer, -1, 0, 10, 10);
+
+        buffer.position(2);
+        assertIndex(buffer, -1, 2, 10, 10);
+
+        buffer.mark();
+        assertIndex(buffer, 2, 2, 10, 10);
+
+        buffer.position(5);
+        assertIndex(buffer, 2, 5, 10, 10);
+
+        buffer.reset();
+        assertIndex(buffer, 2, 2, 10, 10);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingClear_thenOK() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertIndex(buffer, -1, 0, 10, 10);
+
+        // change index
+        buffer.position(2);
+        buffer.mark();
+        buffer.position(5);
+        buffer.limit(8);
+        assertIndex(buffer, 2, 5, 8, 10);
+
+        // clear
+        buffer.clear();
+        assertIndex(buffer, -1, 0, 10, 10);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingFlip_thenOK() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertIndex(buffer, -1, 0, 10, 10);
+
+        // change index
+        buffer.position(2);
+        buffer.mark();
+        buffer.position(5);
+        buffer.limit(8);
+        assertIndex(buffer, 2, 5, 8, 10);
+
+        // flip
+        buffer.flip();
+        assertIndex(buffer, -1, 0, 5, 10);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingRewind_thenOK() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertIndex(buffer, -1, 0, 10, 10);
+
+        // change index
+        buffer.position(2);
+        buffer.mark();
+        buffer.position(5);
+        buffer.limit(8);
+        assertIndex(buffer, 2, 5, 8, 10);
+
+        // rewind
+        buffer.rewind();
+        assertIndex(buffer, -1, 0, 8, 10);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingCompact_thenOK() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertIndex(buffer, -1, 0, 10, 10);
+
+        // change index
+        buffer.position(2);
+        buffer.mark();
+        buffer.position(5);
+        buffer.limit(8);
+        assertIndex(buffer, 2, 5, 8, 10);
+
+        // compact
+        buffer.compact();
+        assertIndex(buffer, -1, 3, 10, 10);
+    }
+
+    @Test
+    public void givenBufferIndex_whenUsingRemain_thenOK() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+
+        // change index
+        buffer.position(2);
+        buffer.limit(8);
+
+        // remain
+        boolean flag = buffer.hasRemaining();
+        int remaining = buffer.remaining();
+
+        // assert
+        assertTrue(flag);
+        assertEquals(6, remaining);
+    }
+
+    @Test(expected = BufferUnderflowException.class)
+    public void givenNotEnoughRemaining_WhenCallingGetInt_thenBufferUnderflowException() {
+        ByteBuffer buffer = ByteBuffer.allocate(2);
+        buffer.getInt();
+    }
+
+    @Test(expected = BufferOverflowException.class)
+    public void givenNotEnoughRemaining_WhenCallingPutInt_thenBufferOverflowException() {
+        ByteBuffer buffer = ByteBuffer.allocate(2);
+        buffer.putInt(10);
+    }
+
+    @Test
+    public void givenBufferView_whenUsingDuplicate_thenOK() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertIndex(buffer, -1, 0, 10, 10);
+
+        // change index
+        buffer.position(2);
+        buffer.mark();
+        buffer.position(5);
+        buffer.limit(8);
+        assertIndex(buffer, 2, 5, 8, 10);
+
+        // view
+        ByteBuffer view = buffer.duplicate();
+        assertIndex(view, 2, 5, 8, 10);
+    }
+
+    @Test
+    public void givenBufferView_whenUsingSlice_thenOK() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertIndex(buffer, -1, 0, 10, 10);
+
+        // change index
+        buffer.position(2);
+        buffer.mark();
+        buffer.position(5);
+        buffer.limit(8);
+        assertIndex(buffer, 2, 5, 8, 10);
+
+        // view
+        ByteBuffer view = buffer.slice();
+        assertIndex(view, -1, 0, 3, 3);
+    }
+
+    @Test
+    public void givenBufferView_whenUsingAsReaOnlyBuffer_thenOK() {
+        // create instance
+        ByteBuffer buffer = ByteBuffer.allocate(10);
+        assertIndex(buffer, -1, 0, 10, 10);
+
+        // change index
+        buffer.position(2);
+        buffer.mark();
+        buffer.position(5);
+        buffer.limit(8);
+        assertIndex(buffer, 2, 5, 8, 10);
+
+        // view
+        ByteBuffer view = buffer.asReadOnlyBuffer();
+        assertIndex(view, 2, 5, 8, 10);
+    }
+
+    @Test
+    public void givenBufferView_whenUsingAsIntBuffer_thenOK() {
+        // create instance
+        byte[] bytes = new byte[]{
+                (byte) 0xCA, (byte) 0xFE, (byte) 0xBA, (byte) 0xBE, // CAFEBABE ---> cafebabe
+                (byte) 0xF0, (byte) 0x07, (byte) 0xBA, (byte) 0x11, // F007BA11 ---> football
+                (byte) 0x0F, (byte) 0xF1, (byte) 0xCE               // 0FF1CE   ---> office
+        };
+        ByteBuffer buffer = ByteBuffer.wrap(bytes);
+        assertIndex(buffer, -1, 0, 11, 11);
+
+        // view
+        IntBuffer intBuffer = buffer.asIntBuffer();
+        int capacity = intBuffer.capacity();
+        assertEquals(2, capacity);
+        assertIndex(intBuffer, -1, 0, 2, 2);
+    }
+
+    @Test
+    public void givenByteOrder_whenUsingBigEndian_thenOK() {
+        // create instance
+        byte[] bytes = new byte[]{(byte) 0xCA, (byte) 0xFE, (byte) 0xBA, (byte) 0xBE};
+        ByteBuffer buffer = ByteBuffer.wrap(bytes);
+
+        // change byte order
+        buffer.order(ByteOrder.BIG_ENDIAN);
+        int val = buffer.getInt();
+
+        // assert
+        assertEquals(0xCAFEBABE, val);
+    }
+
+    @Test
+    public void givenByteOrder_whenUsingLittleEndian_thenOK() {
+        // create instance
+        byte[] bytes = new byte[]{(byte) 0xCA, (byte) 0xFE, (byte) 0xBA, (byte) 0xBE};
+        ByteBuffer buffer = ByteBuffer.wrap(bytes);
+
+        // change byte order
+        buffer.order(ByteOrder.LITTLE_ENDIAN);
+        int val = buffer.getInt();
+
+        // assert
+        assertEquals(0xBEBAFECA, val);
+    }
+
+    @Test
+    public void givenComparing_whenUsingEqualsAndCompareTo_thenOK() {
+        // create instance
+        byte[] bytes1 = "World".getBytes(StandardCharsets.UTF_8);
+        byte[] bytes2 = "HelloWorld".getBytes(StandardCharsets.UTF_8);
+        ByteBuffer buffer1 = ByteBuffer.wrap(bytes1);
+        ByteBuffer buffer2 = ByteBuffer.wrap(bytes2);
+
+        // change index
+        buffer2.position(5);
+
+        // equals and compareTo
+        boolean equal = buffer1.equals(buffer2);
+        int result = buffer1.compareTo(buffer2);
+
+        // assert
+        assertTrue(equal);
+        assertEquals(0, result);
+    }
+
+    private void assertIndex(Buffer buffer, int mark, int position, int limit, int capacity) {
+        assertEquals(mark, getMark(buffer));
+        assertEquals(position, buffer.position());
+        assertEquals(limit, buffer.limit());
+        assertEquals(capacity, buffer.capacity());
+    }
+
+    private int getMark(Buffer buffer) {
+        try {
+            Class<?> clazz = Buffer.class;
+            Field f = clazz.getDeclaredField("mark");
+            f.setAccessible(true);
+            Object result = f.get(buffer);
+            return (int) result;
+        } catch (NoSuchFieldException | IllegalAccessException e) {
+            e.printStackTrace();
+        }
+        return -1;
+    }
+}

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

@@ -10,4 +10,5 @@ This module contains articles about core Java Security
 - [HMAC in Java](https://www.baeldung.com/java-hmac)
 - [Generating a Secure AES Key in Java](https://www.baeldung.com/java-secure-aes-key)
 - [Computing an X509 Certificate’s Thumbprint in Java](https://www.baeldung.com/java-x509-certificate-thumbprint)
+- [Error: “trustAnchors parameter must be non-empty”](https://www.baeldung.com/java-trustanchors-parameter-must-be-non-empty)
 - More articles: [[<-- prev]](/core-java-modules/core-java-security-2)

docker/README.md

@@ -6,3 +6,4 @@
 - [How To Configure Java Heap Size Inside a Docker Container](https://www.baeldung.com/ops/docker-jvm-heap-size)
 - [Dockerfile Strategies for Git](https://www.baeldung.com/ops/dockerfile-git-strategies)
 - [How to Get Docker-Compose to Always Use the Latest Image](https://www.baeldung.com/ops/docker-compose-latest-image)
+- [How to Include Files Outside of Docker’s Build Context](https://www.baeldung.com/ops/docker-include-files-outside-build-context)

docker/docker-include-outside-build-context/projects/config/Dockerfile

@@ -0,0 +1,2 @@
+FROM nginx:latest
+COPY nginx.conf /etc/nginx/nginx.conf

docker/docker-include-outside-build-context/projects/config/nginx.conf

@@ -0,0 +1,8 @@
+events {}  
+  
+http {  
+ server {  
+    listen 80;
+    index index.html;
+  }  
+}

docker/docker-include-outside-build-context/projects/sample-site/docker/Dockerfile

@@ -0,0 +1,3 @@
+FROM nginx:latest
+COPY sample-site/html/* /etc/nginx/html/
+COPY config/nginx.conf /etc/nginx/nginx.conf

docker/docker-include-outside-build-context/projects/sample-site/docker/Dockerfile-from-base

@@ -0,0 +1,2 @@
+FROM sample-site-base:latest
+COPY html/* /etc/nginx/html/

docker/docker-include-outside-build-context/projects/sample-site/docker/Dockerfile-script

@@ -0,0 +1,3 @@
+FROM nginx:latest
+COPY html/* /etc/nginx/html/
+COPY config/nginx.conf /etc/nginx/nginx.conf

docker/docker-include-outside-build-context/projects/sample-site/docker/build-docker.sh

@@ -0,0 +1,6 @@
+mkdir tmp-context
+cp -R ../html tmp-context/
+cp -R ../../config tmp-context/
+cp Dockerfile-script tmp-context/Dockerfile
+docker build -t sample-site:latest tmp-context
+rm -rf tmp-context

docker/docker-include-outside-build-context/projects/sample-site/html/index.html

@@ -0,0 +1,10 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <title>Sample Site</title>
+</head>
+<body>
+  <h2>Welcome to the first page of the site</h2>
+</body>
+</html>

gradle/gradle-source-vs-target-compatibility/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Gradle: sourceCompatiblity vs targetCompatibility](https://www.baeldung.com/gradle-sourcecompatiblity-vs-targetcompatibility)

java-collections-maps-3/README.md

@@ -7,3 +7,4 @@
 - [Update the Value Associated With a Key in a HashMap](https://www.baeldung.com/java-hashmap-update-value-by-key)
 - [Java Map – keySet() vs. entrySet() vs. values() Methods](https://www.baeldung.com/java-map-entries-methods)
 - [Java IdentityHashMap Class and Its Use Cases](https://www.baeldung.com/java-identityhashmap)
+- [How to Invert a Map in Java](https://www.baeldung.com/java-invert-map)

java-collections-maps-3/src/main/java/com/baeldung/map/invert/InvertHashMapExample.java

@@ -0,0 +1,59 @@
+package com.baeldung.map.invert;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.stream.Collectors;
+
+public class InvertHashMapExample {
+
+    public static void main(String[] args) {
+
+        Map<String, Integer> map = new HashMap<>();
+        map.put("first", 1);
+        map.put("second", 2);
+        System.out.println(map);
+
+        invertMapUsingForLoop(map);
+        invertMapUsingStreams(map);
+        invertMapUsingMapper(map);
+
+        map.put("two", 2);
+        invertMapUsingGroupingBy(map);
+    }
+
+    public static <V, K> Map<V, K> invertMapUsingForLoop(Map<K, V> map) {
+        Map<V, K> inversedMap = new HashMap<V, K>();
+        for (Entry<K, V> entry : map.entrySet()) {
+            inversedMap.put(entry.getValue(), entry.getKey());
+        }
+        System.out.println(inversedMap);
+        return inversedMap;
+    }
+
+    public static <V, K> Map<V, K> invertMapUsingStreams(Map<K, V> map) {
+        Map<V, K> inversedMap = map.entrySet()
+            .stream()
+            .collect(Collectors.toMap(Entry::getValue, Entry::getKey));
+        System.out.println(inversedMap);
+        return inversedMap;
+    }
+
+    public static <K, V> Map<V, K> invertMapUsingMapper(Map<K, V> sourceMap) {
+        Map<V, K> inversedMap = sourceMap.entrySet()
+            .stream()
+            .collect(Collectors.toMap(Entry::getValue, Entry::getKey, (oldValue, newValue) -> oldValue));
+        System.out.println(inversedMap);
+        return inversedMap;
+    }
+
+    public static <V, K> Map<V, List<K>> invertMapUsingGroupingBy(Map<K, V> map) {
+        Map<V, List<K>> inversedMap = map.entrySet()
+            .stream()
+            .collect(Collectors.groupingBy(Map.Entry::getValue, Collectors.mapping(Map.Entry::getKey, Collectors.toList())));
+        System.out.println(inversedMap);
+        return inversedMap;
+    }
+
+}

java-collections-maps-3/src/test/java/com/baeldung/map/invert/InvertHashMapUnitTest.java

@@ -0,0 +1,72 @@
+package com.baeldung.map.invert;
+
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+public class InvertHashMapUnitTest {
+
+    Map<String, Integer> sourceMap;
+
+    @BeforeEach
+    void setup() {
+        sourceMap = new HashMap<>();
+        sourceMap.put("Sunday", 0);
+        sourceMap.put("Monday", 1);
+        sourceMap.put("Tuesday", 2);
+        sourceMap.put("Wednesday", 3);
+        sourceMap.put("Thursday", 4);
+        sourceMap.put("Friday", 5);
+        sourceMap.put("Saturday", 6);
+    }
+
+    @Test
+    void givenSourceMap_whenUsingForLoop_returnsInvertedMap() {
+        Map<Integer, String> inversedMap = InvertHashMapExample.invertMapUsingForLoop(sourceMap);
+        
+        assertNotNull(inversedMap);
+        assertEquals(sourceMap.size(), inversedMap.size());
+        assertEquals("Monday", inversedMap.get(1));
+    }
+
+    @Test
+    void givenSourceMap_whenUsingStreams_returnsInvertedMap() {
+        Map<Integer, String> inversedMap = InvertHashMapExample.invertMapUsingStreams(sourceMap);
+        
+        assertNotNull(inversedMap);
+        assertEquals(sourceMap.size(), inversedMap.size());
+        assertEquals("Monday", inversedMap.get(1));
+    }
+
+    @Test
+    void givenSourceMap_whenUsingMapper_returnsInvertedMap() {
+        Map<Integer, String> inversedMap = InvertHashMapExample.invertMapUsingMapper(sourceMap);
+        
+        assertNotNull(inversedMap);
+        assertEquals(sourceMap.size(), inversedMap.size());
+        assertEquals("Monday", inversedMap.get(1));
+    }
+
+    @Test
+    void givenSourceMapWithDuplicateValues_whenUsingGroupBy_returnsInvertedMap() {
+        sourceMap.put("MONDAY", 1);
+        Map<Integer, List<String>> inversedMap = InvertHashMapExample.invertMapUsingGroupingBy(sourceMap);
+        
+        assertNotNull(inversedMap);
+        assertNotEquals(sourceMap.size(), inversedMap.size()); // duplicate keys are merged now
+        assertEquals(2, inversedMap.get(1).size());
+        assertTrue(inversedMap.get(1).contains("Monday"));
+        assertTrue(inversedMap.get(1).contains("MONDAY"));
+    }
+
+}

java-native/README.md

@@ -7,3 +7,4 @@ This module contains articles about the Java Native Interface (JNI).
 - [Guide to JNI (Java Native Interface)](https://www.baeldung.com/jni)
 - [Using JNA to Access Native Dynamic Libraries](https://www.baeldung.com/java-jna-dynamic-libraries)
 - [Check if a Java Program Is Running in 64-Bit or 32-Bit JVM](https://www.baeldung.com/java-detect-jvm-64-or-32-bit)
+- [How to use JNI’s RegisterNatives() method?](https://www.baeldung.com/jni-registernatives)

javax-servlets-2/README.md

@@ -0,0 +1,5 @@
+## Servlets
+
+This module contains articles about Servlets.
+
+### Relevant Articles:

javax-servlets-2/pom.xml

@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.javax-servlets</groupId>
+    <artifactId>javax-servlets-2</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>javax-servlets-2</name>
+    <packaging>war</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <!-- File Uploading -->
+        <dependency>
+            <groupId>commons-fileupload</groupId>
+            <artifactId>commons-fileupload</artifactId>
+            <version>${commons-fileupload.version}</version>
+        </dependency>
+        <!-- Servlet -->
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>javax.servlet-api</artifactId>
+            <version>${javax.servlet-api.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet.jsp</groupId>
+            <artifactId>javax.servlet.jsp-api</artifactId>
+            <version>${javax.servlet.jsp-api.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>jstl</artifactId>
+            <version>${jstl.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpclient</artifactId>
+            <version>${org.apache.httpcomponents.version}</version>
+            <scope>test</scope>
+            <exclusions>
+                <exclusion>
+                    <artifactId>commons-logging</artifactId>
+                    <groupId>commons-logging</groupId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <org.apache.httpcomponents.version>4.5.13</org.apache.httpcomponents.version>
+        <javax.servlet-api.version>4.0.1</javax.servlet-api.version>
+    </properties>
+</project>

javax-servlets-2/src/main/java/com/baeldung/user/check/User.java

@@ -0,0 +1,80 @@
+package com.baeldung.user.check;
+
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+
+/**
+ * @since 6 de fev de 2022
+ * @author ulisses
+ */
+public class User implements Serializable {
+    private static final long serialVersionUID = 1L;
+
+    protected static final HashMap<String, User> DB = new HashMap<>();
+    static {
+        DB.put("admin", new User("admin", "password"));
+        DB.put("user", new User("user", "pass"));
+    }
+
+    private String name;
+    private String password;
+
+    private List<Date> logins = new ArrayList<Date>();
+
+    public User(String name, String password) {
+        this.name = name;
+        this.password = password;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public List<Date> getLogins() {
+        return logins;
+    }
+
+    public void setLogins(List<Date> logins) {
+        this.logins = logins;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((name == null) ? 0 : name.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        User other = (User) obj;
+        if (name == null) {
+            if (other.name != null)
+                return false;
+        } else if (!name.equals(other.name))
+            return false;
+        return true;
+    }
+}

javax-servlets-2/src/main/java/com/baeldung/user/check/UserCheckFilter.java

@@ -0,0 +1,46 @@
+package com.baeldung.user.check;
+
+import java.io.IOException;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.annotation.WebFilter;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+@WebFilter("/user-check/*")
+public class UserCheckFilter implements Filter {
+    public static void forward(HttpServletRequest request, HttpServletResponse response, String page) throws ServletException, IOException {
+        request.getRequestDispatcher("/WEB-INF/user.check" + page)
+            .forward(request, response);
+    }
+
+    @Override
+    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
+        if (!(req instanceof HttpServletRequest)) {
+            throw new ServletException("Can only process HttpServletRequest");
+        }
+
+        if (!(res instanceof HttpServletResponse)) {
+            throw new ServletException("Can only process HttpServletResponse");
+        }
+
+        HttpServletRequest request = (HttpServletRequest) req;
+        HttpServletResponse response = (HttpServletResponse) res;
+
+        request.setAttribute("origin", request.getRequestURI());
+
+        if (!request.getRequestURI()
+            .contains("login") && request.getSession(false) == null) {
+            response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
+            forward(request, response, "/login.jsp");
+            // we return here so the original servlet is not processed
+            return;
+        }
+
+        chain.doFilter(request, response);
+    }
+}

javax-servlets-2/src/main/java/com/baeldung/user/check/UserCheckLoginServlet.java

@@ -0,0 +1,56 @@
+package com.baeldung.user.check;
+
+import java.io.IOException;
+import java.util.Date;
+
+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 javax.servlet.http.HttpSession;
+
+@WebServlet("/user-check/login")
+public class UserCheckLoginServlet extends HttpServlet {
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        if (request.getSession(false) != null) {
+            response.sendRedirect(request.getContextPath() + "/user-check/home");
+            return;
+        }
+
+        String referer = (String) request.getAttribute("origin");
+        request.setAttribute("origin", referer);
+        UserCheckFilter.forward(request, response, "/login.jsp");
+    }
+
+    @Override
+    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        String key = request.getParameter("name");
+        String pass = request.getParameter("password");
+
+        User user = User.DB.get(key);
+        if (user == null || !user.getPassword()
+            .equals(pass)) {
+            response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
+            request.setAttribute("origin", request.getParameter("origin"));
+            request.setAttribute("error", "invalid login");
+            UserCheckFilter.forward(request, response, "/login.jsp");
+            return;
+        }
+
+        user.getLogins()
+            .add(new Date());
+
+        HttpSession session = request.getSession();
+        session.setAttribute("user", user);
+
+        String origin = request.getParameter("origin");
+        if (origin == null || origin.contains("login"))
+            origin = "./";
+
+        response.sendRedirect(origin);
+    }
+}

javax-servlets-2/src/main/java/com/baeldung/user/check/UserCheckLogoutServlet.java

@@ -0,0 +1,26 @@
+package com.baeldung.user.check;
+
+import java.io.IOException;
+
+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 javax.servlet.http.HttpSession;
+
+@WebServlet("/user-check/logout")
+public class UserCheckLogoutServlet extends HttpServlet {
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        HttpSession session = request.getSession(false);
+        if (session != null) {
+            session.invalidate();
+        }
+
+        request.setAttribute("loggedOut", true);
+        response.sendRedirect("./");
+    }
+}

javax-servlets-2/src/main/java/com/baeldung/user/check/UserCheckServlet.java

@@ -0,0 +1,28 @@
+package com.baeldung.user.check;
+
+import java.io.IOException;
+
+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 javax.servlet.http.HttpSession;
+
+@WebServlet(name = "home", urlPatterns = { "/user-check/", "/user-check", "/user-check/home" })
+public class UserCheckServlet extends HttpServlet {
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        HttpSession session = request.getSession(false);
+        if (session == null || session.getAttribute("user") == null) {
+            throw new IllegalStateException("user not logged in");
+        }
+
+        User user = (User) session.getAttribute("user");
+        request.setAttribute("user", user);
+
+        UserCheckFilter.forward(request, response, "/home.jsp");
+    }
+}

javax-servlets-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>

javax-servlets-2/src/main/webapp/WEB-INF/user.check/home.jsp

@@ -0,0 +1,31 @@
+<%@ page contentType="text/html;charset=UTF-8" session="false"%>
+<%@ taglib uri="http://java.sun.com/jstl/core_rt" prefix="c"%>
+
+<html>
+    <head>
+        <title>login success - current session info</title>
+    </head>
+    <body>
+        <section>
+            <h2>user info</h2>
+            <div>
+                <span>name: ${user.name}</span>
+            </div>
+    
+            <div>
+                <span>logins:</span>
+                <ul>
+                    <c:forEach var="login" items="${user.logins}">
+                        <li>${login}</li>
+                    </c:forEach>
+                </ul>
+            </div>
+    
+            <div>
+                <a href="${pageContext.request.contextPath}/user-check/logout">
+                    logout
+                </a>
+            </div>
+        </section>
+    </body>
+</html>

javax-servlets-2/src/main/webapp/WEB-INF/user.check/login.jsp

@@ -0,0 +1,33 @@
+<%@ page contentType="text/html;charset=UTF-8" session="false"%>
+<%@ taglib uri="http://java.sun.com/jstl/core_rt" prefix="c"%>
+
+<html>
+    <head>
+        <title>login</title>
+    </head>
+    <body>
+        <form action="${pageContext.request.contextPath}/user-check/login"
+          method="POST">
+            <input type="hidden" name="origin" value="${origin}">
+            <c:if test="${not empty origin}">
+                <div>* redirected to login from: ${origin}</div>
+            </c:if>
+    
+            <c:if test="${not empty error}">
+                <div>* error: ${error}</div>
+            </c:if>
+    
+            <fieldset>
+                <legend>credentials</legend>
+                
+                <label for="name">name</label> 
+                <input type="text" name="name">
+    
+                <label for="password">password</label> 
+                <input type="password" name="password"> 
+                
+                <input type="submit">
+            </fieldset>
+        </form>
+    </body>
+</html>

javax-servlets-2/src/test/java/com/baeldung/user/check/UserCheckServletLiveTest.java

@@ -0,0 +1,98 @@
+package com.baeldung.user.check;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.http.client.entity.UrlEncodedFormEntity;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.client.methods.HttpPost;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClientBuilder;
+import org.apache.http.impl.client.LaxRedirectStrategy;
+import org.apache.http.message.BasicNameValuePair;
+import org.apache.http.util.EntityUtils;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+@RunWith(MockitoJUnitRunner.class)
+public class UserCheckServletLiveTest {
+    private static final String BASE_URL = "http://localhost:8080/javax-servlets-2/user-check";
+
+    @Mock
+    HttpServletRequest request;
+
+    @Mock
+    HttpServletResponse response;
+
+    private CloseableHttpClient buildClient() {
+        return HttpClientBuilder.create()
+            .setRedirectStrategy(new LaxRedirectStrategy())
+            .build();
+    }
+
+    @Test
+    public void whenCorrectCredentials_thenLoginSucceeds() throws Exception {
+        try (CloseableHttpClient client = buildClient()) {
+            HttpPost post = new HttpPost(BASE_URL + "/login");
+
+            List<BasicNameValuePair> form = new ArrayList<>();
+            form.add(new BasicNameValuePair("name", "admin"));
+            form.add(new BasicNameValuePair("password", "password"));
+
+            post.setEntity(new UrlEncodedFormEntity(form));
+            try (CloseableHttpResponse response = client.execute(post)) {
+                String body = EntityUtils.toString(response.getEntity());
+
+                assertTrue(response.getStatusLine()
+                    .getStatusCode() == 200);
+
+                assertTrue(body.contains("login success"));
+            }
+        }
+    }
+
+    @Test
+    public void whenIncorrectCredentials_thenLoginFails() throws Exception {
+        try (CloseableHttpClient client = buildClient()) {
+            HttpPost post = new HttpPost(BASE_URL + "/login");
+
+            List<BasicNameValuePair> form = new ArrayList<>();
+            form.add(new BasicNameValuePair("name", "admin"));
+            form.add(new BasicNameValuePair("password", "invalid"));
+
+            post.setEntity(new UrlEncodedFormEntity(form));
+            try (CloseableHttpResponse response = client.execute(post)) {
+                String body = EntityUtils.toString(response.getEntity());
+
+                assertTrue(response.getStatusLine()
+                    .getStatusCode() == 401);
+
+                assertTrue(body.contains("invalid login"));
+            }
+        }
+    }
+
+    @Test
+    public void whenNotLoggedIn_thenRedirectedToLoginPage() throws Exception {
+        try (CloseableHttpClient client = buildClient()) {
+            HttpGet get = new HttpGet(BASE_URL + "/home");
+
+            try (CloseableHttpResponse response = client.execute(get)) {
+                String body = EntityUtils.toString(response.getEntity());
+
+                assertTrue(response.getStatusLine()
+                    .getStatusCode() == 401);
+
+                assertTrue(body.contains("redirected to login"));
+            }
+        }
+    }
+}

jta/pom.xml

@@ -16,6 +16,18 @@
         <relativePath>../parent-boot-2</relativePath>
     </parent>
     
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -37,6 +49,7 @@
 
     <properties>
         <spring-boot.version>2.4.7</spring-boot.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

maven-modules/maven-generate-war/pom.xml

@@ -63,6 +63,7 @@
 
     <properties>
         <java.version>11</java.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

parent-spring-5/pom.xml

@@ -24,7 +24,7 @@
     </dependencies>
 
     <properties>
-        <spring.version>5.3.13</spring.version>
+        <spring.version>5.3.16</spring.version>
         <spring-security.version>5.6.0</spring-security.version>
         <spring-boot-starter-test.version>1.5.10.RELEASE</spring-boot-starter-test.version>
     </properties>

patterns/enterprise-patterns/pom.xml

@@ -48,6 +48,13 @@
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
         </dependencies>
     </dependencyManagement>
 
@@ -63,6 +70,7 @@
     <properties>
         <camel.version>3.7.4</camel.version>
         <spring-boot.version>2.2.2.RELEASE</spring-boot.version>
+         <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

persistence-modules/hibernate-queries/README.md

@@ -8,3 +8,4 @@ This module contains articles about use of Queries in Hibernate.
 - [Get All Data from a Table with Hibernate](https://www.baeldung.com/hibernate-select-all)
 - [Hibernate Named Query](https://www.baeldung.com/hibernate-named-query)
 - [Hibernate Query Plan Cache](https://www.baeldung.com/hibernate-query-plan-cache)
+- [Hibernate’s addScalar() Method](https://www.baeldung.com/hibernate-addscalar)

persistence-modules/spring-data-dynamodb/pom.xml

@@ -24,6 +24,13 @@
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
         </dependencies>
     </dependencyManagement>
 
@@ -184,6 +191,7 @@
         <dynamodblocal.repository.url>https://s3-us-west-2.amazonaws.com/dynamodb-local/release</dynamodblocal.repository.url>
         <maven-dependency-plugin.version>3.1.1</maven-dependency-plugin.version>
         <spring-boot.version>2.4.7</spring-boot.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

pom.xml

@@ -459,6 +459,7 @@
                 <module>java-vavr-stream</module>
                 <module>java-websocket</module>
                 <module>javax-servlets</module>
+                <module>javax-servlets-2</module>
                 <module>javaxval</module>
                 <module>jaxb</module>
                 <module>jee-7</module>
@@ -943,6 +944,7 @@
                 <module>java-vavr-stream</module>
                 <module>java-websocket</module>
                 <module>javax-servlets</module>
+                <module>javax-servlets-2</module>
                 <module>javaxval</module>
                 <module>jaxb</module>
                 <module>jee-7</module>
@@ -1344,6 +1346,7 @@
                  <module>quarkus-vs-springboot</module>
                  <module>quarkus-jandex</module>
 		 <module>spring-boot-modules/spring-boot-cassandre</module>
+		 <module>spring-boot-modules/spring-boot-camel</module>	 
                  <module>testing-modules/testing-assertions</module>
             </modules>
         </profile>
@@ -1401,6 +1404,7 @@
                 <module>quarkus-vs-springboot</module>
                 <module>quarkus-jandex</module>
 		<module>spring-boot-modules/spring-boot-cassandre</module>
+		<module>spring-boot-modules/spring-boot-camel</module>
                 <module>testing-modules/testing-assertions</module>
             </modules>
         </profile>

quarkus-vs-springboot/spring-project/pom.xml

@@ -187,6 +187,7 @@
         <java.version>11</java.version>
         <repackage.classifier />
         <spring-native.version>0.11.0-RC1</spring-native.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-5-autowiring-beans/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Spring @Autowired Field Null – Common Causes and Solutions](https://www.baeldung.com/spring-autowired-field-null)

spring-5-data-reactive/pom.xml

@@ -14,6 +14,18 @@
         <relativePath>../parent-boot-2</relativePath>
     </parent>
     
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <dependencies>
         <dependency>
             <groupId>io.projectreactor</groupId>
@@ -138,6 +150,7 @@
         <reactor-core.version>3.3.1.RELEASE</reactor-core.version>
         <!-- This spring-boot.version is set manually, For upgrading this please refer http://team.baeldung.com/browse/JAVA-2802 -->
         <spring-boot.version>2.2.6.RELEASE</spring-boot.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-activiti/pom.xml

@@ -17,6 +17,18 @@
         <relativePath>../parent-boot-1</relativePath>
     </parent>
     
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <dependencies>
         <dependency>
             <groupId>org.activiti</groupId>
@@ -59,6 +71,7 @@
 
     <properties>
         <activiti.version>6.0.0</activiti.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-boot-modules/pom.xml

@@ -36,7 +36,6 @@
         <module>spring-boot-deployment</module>
         <module>spring-boot-di</module>
         <module>spring-boot-disable-logging</module>
-        <module>spring-boot-camel</module>
         <module>spring-boot-ci-cd</module>
         <!-- <module>spring-boot-cli</module> --> <!-- Not a maven project -->
         <module>spring-boot-custom-starter</module>
@@ -51,6 +50,7 @@
         <!-- <module>spring-boot-keycloak</module> --> <!-- Fixing under JAVA-8271 -->
         <module>spring-boot-libraries</module>
         <module>spring-boot-libraries-2</module>
+        <module>spring-boot-libraries-comparison</module>
         <module>spring-boot-logging-log4j2</module>
         <module>spring-boot-multiple-datasources</module>
         <module>spring-boot-mvc</module>

spring-boot-modules/spring-boot-2/pom.xml

@@ -62,7 +62,7 @@
     </build>
 
     <properties>
-        <log4j2.version>2.14.1</log4j2.version>
+        <log4j2.version>2.17.1</log4j2.version>
         <spring-core.version>5.3.15</spring-core.version>
         <maven.compiler.target>11</maven.compiler.target>
         <maven.compiler.source>11</maven.compiler.source>

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

@@ -16,22 +16,22 @@
 
     <dependencies>
         <dependency>
-            <groupId>org.apache.camel</groupId>
+            <groupId>org.apache.camel.springboot</groupId>
             <artifactId>camel-servlet-starter</artifactId>
             <version>${camel.version}</version>
         </dependency>
         <dependency>
-            <groupId>org.apache.camel</groupId>
+            <groupId>org.apache.camel.springboot</groupId>
             <artifactId>camel-jackson-starter</artifactId>
             <version>${camel.version}</version>
         </dependency>
         <dependency>
-            <groupId>org.apache.camel</groupId>
+            <groupId>org.apache.camel.springboot</groupId>
             <artifactId>camel-swagger-java-starter</artifactId>
             <version>${camel.version}</version>
         </dependency>
         <dependency>
-            <groupId>org.apache.camel</groupId>
+            <groupId>org.apache.camel.springboot</groupId>
             <artifactId>camel-spring-boot-starter</artifactId>
             <version>${camel.version}</version>
         </dependency>
@@ -64,7 +64,8 @@
     </build>
 
     <properties>
-        <camel.version>3.0.0-M4</camel.version>
+        <java.version>11</java.version>
+        <camel.version>3.15.0</camel.version>
     </properties>
 
 </project>

spring-boot-modules/spring-boot-libraries-comparison/README.md

@@ -0,0 +1,7 @@
+## Spring Boot Libraries
+
+This module contains articles about various Spring Boot libraries Comparison
+
+### Relevant Articles:
+
+- [GraphQL vs REST](https://www.baeldung.com/graphql-vs-rest)

spring-boot-modules/spring-boot-libraries-comparison/pom.xml

@@ -0,0 +1,46 @@
+<?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>spring-boot-libraries-comparison</artifactId>
+
+    <parent>
+        <groupId>com.baeldung.spring-boot-modules</groupId>
+        <artifactId>spring-boot-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.data</groupId>
+            <artifactId>spring-data-jpa</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-spring-boot-starter</artifactId>
+            <version>${graphql-spring-boot-starter.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphql-java-tools</artifactId>
+            <version>${graphql-java-tools.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.graphql-java</groupId>
+            <artifactId>graphiql-spring-boot-starter</artifactId>
+            <version>${graphql-spring-boot-starter.version}</version>
+        </dependency>
+    </dependencies>
+
+
+    <properties>
+        <graphql-spring-boot-starter.version>5.0.2</graphql-spring-boot-starter.version>
+        <graphql-java-tools.version>5.2.4</graphql-java-tools.version>
+    </properties>
+
+</project>

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/GraphqlVsRestApplication.java

@@ -0,0 +1,19 @@
+package com.baeldung.graphqlvsrest;
+
+import com.baeldung.graphqlvsrest.configuration.GraphqlConfiguration;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration;
+import org.springframework.context.annotation.Import;
+
+@SpringBootApplication
+@Import(GraphqlConfiguration.class)
+@EnableAutoConfiguration(exclude = {SecurityAutoConfiguration.class})
+public class GraphqlVsRestApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(GraphqlVsRestApplication.class, args);
+    }
+
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/configuration/GraphqlConfiguration.java

@@ -0,0 +1,35 @@
+package com.baeldung.graphqlvsrest.configuration;
+
+import com.baeldung.graphqlvsrest.repository.OrderRepository;
+import com.baeldung.graphqlvsrest.resolver.Mutation;
+import com.baeldung.graphqlvsrest.resolver.ProductResolver;
+import com.baeldung.graphqlvsrest.resolver.Query;
+import com.baeldung.graphqlvsrest.repository.ProductRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class GraphqlConfiguration {
+
+    @Autowired
+    ProductRepository productRepository;
+
+    @Autowired
+    OrderRepository orderRepository;
+
+    @Bean
+    public Query query() {
+        return new Query(productRepository);
+    }
+
+    @Bean
+    public ProductResolver productResolver(){
+        return new ProductResolver(orderRepository);
+    }
+
+    @Bean
+    public Mutation mutation() {
+        return new Mutation(productRepository);
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/controller/OrderController.java

@@ -0,0 +1,25 @@
+package com.baeldung.graphqlvsrest.controller;
+
+import com.baeldung.graphqlvsrest.entity.Order;
+import com.baeldung.graphqlvsrest.entity.Product;
+import com.baeldung.graphqlvsrest.model.ProductModel;
+import com.baeldung.graphqlvsrest.repository.OrderRepository;
+import com.baeldung.graphqlvsrest.repository.ProductRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.domain.Pageable;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("order")
+public class OrderController {
+
+    @Autowired
+    OrderRepository orderRepository;
+
+    @GetMapping()
+    public List<Order> getOrders(@RequestParam("product-id") Integer productId){
+        return orderRepository.getOrdersByProduct(productId);
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/controller/ProductController.java

@@ -0,0 +1,38 @@
+package com.baeldung.graphqlvsrest.controller;
+
+import com.baeldung.graphqlvsrest.entity.Product;
+import com.baeldung.graphqlvsrest.model.ProductModel;
+import com.baeldung.graphqlvsrest.repository.ProductRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.domain.Pageable;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("product")
+public class ProductController {
+
+    @Autowired
+    ProductRepository productRepository;
+
+    @GetMapping
+    public List<Product> getProducts(Pageable pageable){
+        return productRepository.getProducts(pageable.getPageSize(), pageable.getPageNumber());
+    }
+
+    @GetMapping("/{product-id}")
+    public Product getProducts(@PathVariable("product-id") Integer productId){
+        return productRepository.getProduct(productId);
+    }
+
+    @PostMapping
+    public Product save(@RequestBody ProductModel productModel){
+        return productRepository.save(productModel);
+    }
+
+    @PutMapping("/{product-id}")
+    public Product update(@PathVariable("product-id") Integer productId, @RequestBody ProductModel productModel){
+        return productRepository.update(productId, productModel);
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/entity/Order.java

@@ -0,0 +1,58 @@
+package com.baeldung.graphqlvsrest.entity;
+
+public class Order {
+    private Integer id;
+    private Integer product_id;
+    private String customer_uuid;
+    private String status;
+    private String address;
+    private String creation_date;
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public Integer getProduct_id() {
+        return product_id;
+    }
+
+    public void setProduct_id(Integer product_id) {
+        this.product_id = product_id;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public String getCustomer_uuid() {
+        return customer_uuid;
+    }
+
+    public void setCustomer_uuid(String customer_uuid) {
+        this.customer_uuid = customer_uuid;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+
+    public String getCreation_date() {
+        return creation_date;
+    }
+
+    public void setCreation_date(String creation_date) {
+        this.creation_date = creation_date;
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/entity/Product.java

@@ -0,0 +1,115 @@
+package com.baeldung.graphqlvsrest.entity;
+
+import com.baeldung.graphqlvsrest.model.ProductModel;
+
+import java.util.List;
+
+public class Product {
+    private Integer id;
+    private String name;
+    private String description;
+    private String status;
+    private String currency;
+    private Double price;
+    private List<String> image_url;
+    private List<String> video_url;
+    private Integer stock;
+    private Float average_rating;
+
+    public Product(Integer id, ProductModel productModel) {
+        this.id = id;
+        this.name = productModel.getName();
+        this.description = productModel.getDescription();
+        this.currency = productModel.getCurrency();
+        this.price = productModel.getPrice();
+        this.stock = productModel.getStock();
+        this.image_url = productModel.getImage_url();
+        this.video_url = productModel.getVideo_url();
+        this.average_rating = 0F;
+        this.status = productModel.getStatus();
+    }
+
+    public Product(){
+
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public String getCurrency() {
+        return currency;
+    }
+
+    public void setCurrency(String currency) {
+        this.currency = currency;
+    }
+
+    public Double getPrice() {
+        return price;
+    }
+
+    public void setPrice(Double price) {
+        this.price = price;
+    }
+
+    public List<String> getImage_url() {
+        return image_url;
+    }
+
+    public void setImage_url(List<String> image_url) {
+        this.image_url = image_url;
+    }
+
+    public List<String> getVideo_url() {
+        return video_url;
+    }
+
+    public void setVideo_url(List<String> video_url) {
+        this.video_url = video_url;
+    }
+
+    public Integer getStock() {
+        return stock;
+    }
+
+    public void setStock(Integer stock) {
+        this.stock = stock;
+    }
+
+    public Float getAverage_rating() {
+        return average_rating;
+    }
+
+    public void setAverage_rating(Float average_rating) {
+        this.average_rating = average_rating;
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/model/ProductModel.java

@@ -0,0 +1,92 @@
+package com.baeldung.graphqlvsrest.model;
+
+import java.util.List;
+
+public class ProductModel {
+    private String name;
+    private String description;
+    private String status;
+    private String currency;
+    private Double price;
+    private List<String> image_url;
+    private List<String> video_url;
+    private Integer stock;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public String getCurrency() {
+        return currency;
+    }
+
+    public void setCurrency(String currency) {
+        this.currency = currency;
+    }
+
+    public Double getPrice() {
+        return price;
+    }
+
+    public void setPrice(Double price) {
+        this.price = price;
+    }
+
+    public List<String> getImage_url() {
+        return image_url;
+    }
+
+    public void setImage_url(List<String> image_url) {
+        this.image_url = image_url;
+    }
+
+    public List<String> getVideo_url() {
+        return video_url;
+    }
+
+    public void setVideo_url(List<String> video_url) {
+        this.video_url = video_url;
+    }
+
+    public Integer getStock() {
+        return stock;
+    }
+
+    public void setStock(Integer stock) {
+        this.stock = stock;
+    }
+
+    @Override
+    public String toString() {
+        return "ProductModel{" +
+                "name='" + name + '\'' +
+                ", description='" + description + '\'' +
+                ", status='" + status + '\'' +
+                ", currency='" + currency + '\'' +
+                ", price=" + price +
+                ", image_url=" + image_url +
+                ", video_url=" + video_url +
+                ", stock=" + stock +
+                '}';
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/repository/OrderRepository.java

@@ -0,0 +1,11 @@
+package com.baeldung.graphqlvsrest.repository;
+
+import com.baeldung.graphqlvsrest.entity.Order;
+import com.baeldung.graphqlvsrest.entity.Product;
+import com.baeldung.graphqlvsrest.model.ProductModel;
+
+import java.util.List;
+
+public interface OrderRepository {
+    List<Order> getOrdersByProduct(Integer productId);
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/repository/ProductRepository.java

@@ -0,0 +1,14 @@
+package com.baeldung.graphqlvsrest.repository;
+
+import com.baeldung.graphqlvsrest.entity.Product;
+import com.baeldung.graphqlvsrest.model.ProductModel;
+
+import java.util.List;
+
+public interface ProductRepository {
+    List<Product> getProducts(Integer pageSize, Integer pageNumber);
+    Product getProduct(Integer id);
+    Product save(ProductModel productModel);
+    Product update(Integer productId, ProductModel productModel);
+
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/repository/impl/OrderRepositoryImpl.java

@@ -0,0 +1,36 @@
+package com.baeldung.graphqlvsrest.repository.impl;
+
+import com.baeldung.graphqlvsrest.entity.Order;
+import com.baeldung.graphqlvsrest.repository.OrderRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+import java.util.UUID;
+import java.util.stream.Collectors;
+
+@Repository
+public class OrderRepositoryImpl implements OrderRepository {
+
+    private static List<Order> orderList = new ArrayList<>();
+
+    public OrderRepositoryImpl() {
+        for (int i = 1; i <= 100; i++){
+            Order order = new Order();
+            order.setId(i);
+            order.setProduct_id(i%10);
+            order.setAddress(UUID.randomUUID().toString());
+            order.setCustomer_uuid(UUID.randomUUID().toString());
+            order.setCreation_date(new Date(System.currentTimeMillis()).toString());
+            order.setStatus("Delivered");
+            orderList.add(order);
+        }
+    }
+
+
+    @Override
+    public List<Order> getOrdersByProduct(Integer productId) {
+        return orderList.stream().filter(order -> order.getProduct_id().equals(productId)).collect(Collectors.toList());
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/repository/impl/ProductRepositoryImpl.java

@@ -0,0 +1,74 @@
+package com.baeldung.graphqlvsrest.repository.impl;
+
+import com.baeldung.graphqlvsrest.entity.Product;
+import com.baeldung.graphqlvsrest.model.ProductModel;
+import com.baeldung.graphqlvsrest.repository.ProductRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+@Repository
+public class ProductRepositoryImpl implements ProductRepository {
+
+    private static List<Product> productList = new ArrayList<>();
+
+    public ProductRepositoryImpl() {
+        for (int i = 1; i <= 10; i++){
+            Product product = new Product();
+            product.setId(i);
+            product.setName(String.format("Product %d", i));
+            product.setDescription(String.format("Product %d description", i));
+            product.setCurrency(String.format("Product %d currency", i));
+            product.setPrice(Double.valueOf(i^2));
+            product.setStock(10);
+            product.setAverage_rating(0F);
+            product.setImage_url(Arrays.asList(String.format("www.baeldung.com/imageurl/%d", i)));
+            product.setVideo_url(Arrays.asList(String.format("www.baeldung.com/videourl/%d", i)));
+            productList.add(product);
+        }
+    }
+
+    @Override
+    public List<Product> getProducts(Integer pageSize, Integer pageNumber) {
+        return productList.stream().skip(pageSize*pageNumber).limit(pageSize).collect(Collectors.toList());
+    }
+
+    @Override
+    public Product getProduct(Integer id) {
+        return productList.stream().filter(product -> product.getId().equals(id)).findFirst().orElse(null);
+    }
+
+    @Override
+    public Product save(ProductModel productModel) {
+        Product product = new Product(productList.size()+1, productModel);
+        productList.add(product);
+        return product;
+    }
+
+    @Override
+    public Product update(Integer productId, ProductModel productModel) {
+        Product product =  getProduct(productId);
+        if (product != null){
+            update(product, productModel);
+        }
+        return product;
+    }
+
+    private void update(Product product, ProductModel productModel){
+        if (productModel != null) {
+            System.out.println(productModel.toString());
+            Optional.ofNullable(productModel.getName()).ifPresent(product::setName);
+            Optional.ofNullable(productModel.getDescription()).ifPresent(product::setDescription);
+            Optional.ofNullable(productModel.getCurrency()).ifPresent(product::setCurrency);
+            Optional.ofNullable(productModel.getImage_url()).ifPresent(product::setImage_url);
+            Optional.ofNullable(productModel.getStock()).ifPresent(product::setStock);
+            Optional.ofNullable(productModel.getStatus()).ifPresent(product::setStatus);
+            Optional.ofNullable(productModel.getVideo_url()).ifPresent(product::setVideo_url);
+            Optional.ofNullable(productModel.getPrice()).ifPresent(product::setPrice);
+        }
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/resolver/Mutation.java

@@ -0,0 +1,22 @@
+package com.baeldung.graphqlvsrest.resolver;
+
+import com.baeldung.graphqlvsrest.entity.Product;
+import com.baeldung.graphqlvsrest.model.ProductModel;
+import com.baeldung.graphqlvsrest.repository.ProductRepository;
+import com.coxautodev.graphql.tools.GraphQLMutationResolver;
+
+public class Mutation implements GraphQLMutationResolver {
+
+    private ProductRepository productRepository;
+    public Mutation(ProductRepository productRepository){
+        this.productRepository = productRepository;
+    }
+
+    public Product saveProduct(ProductModel productModel) {
+        return productRepository.save(productModel);
+    }
+
+    public Product updateProduct(Integer productId, ProductModel productModel) {
+        return productRepository.update(productId, productModel);
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/resolver/ProductResolver.java

@@ -0,0 +1,18 @@
+package com.baeldung.graphqlvsrest.resolver;
+
+import com.baeldung.graphqlvsrest.entity.Order;
+import com.baeldung.graphqlvsrest.entity.Product;
+import com.baeldung.graphqlvsrest.repository.OrderRepository;
+import com.coxautodev.graphql.tools.GraphQLResolver;
+
+import java.util.List;
+
+public class ProductResolver implements GraphQLResolver<Product> {
+    private OrderRepository orderRepository;
+    public ProductResolver(OrderRepository orderRepository){
+        this.orderRepository = orderRepository;
+    }
+    public List<Order> getOrders(Product product){
+        return orderRepository.getOrdersByProduct(product.getId());
+    }
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/java/com/baeldung/graphqlvsrest/resolver/Query.java

@@ -0,0 +1,27 @@
+package com.baeldung.graphqlvsrest.resolver;
+
+import com.baeldung.graphqlvsrest.entity.Order;
+import com.baeldung.graphqlvsrest.entity.Product;
+import com.baeldung.graphqlvsrest.repository.OrderRepository;
+import com.baeldung.graphqlvsrest.repository.ProductRepository;
+import com.coxautodev.graphql.tools.GraphQLQueryResolver;
+
+import java.util.List;
+
+public class Query implements GraphQLQueryResolver {
+
+    private ProductRepository productRepository;
+    public Query(ProductRepository productRepository){
+        this.productRepository = productRepository;
+    }
+
+    public List<Product> getProducts(int pageSize, int pageNumber) {
+        return productRepository.getProducts(pageSize, pageNumber);
+    }
+
+    public Product getProduct(int id) {
+        return productRepository.getProduct(id);
+    }
+
+
+}

spring-boot-modules/spring-boot-libraries-comparison/src/main/resources/graphql/schema.graphqls

@@ -0,0 +1,57 @@
+type Product {
+    id: ID
+    name: String!
+    description: String
+    status: String
+    currency: String!
+    price: Float
+    image_url: [String]
+    video_url: [String]
+    stock: Int
+    average_rating: Float
+    orders:[Order]
+}
+
+type Order{
+    id:ID
+    product_id:Int
+    customer_uuid:String
+    address:String
+    status:String
+    creation_date:String
+}
+
+input ProductModel {
+    name: String!
+    description: String
+    status: String
+    currency: String!
+    price: Float
+    image_url: [String]
+    video_url: [String]
+    stock: Int
+}
+
+input ProductUpdateModel {
+    name: String
+    description: String
+    status: String
+    currency: String
+    price: Float
+    image_url: [String]
+    video_url: [String]
+    stock: Int
+}
+
+
+# The Root Query for the application
+type Query {
+    products(size: Int, page: Int): [Product]!
+    product(id: Int): Product!
+}
+
+# The Root Mutation for the application
+type Mutation {
+    saveProduct(product: ProductModel) : Product!
+    updateProduct(id: Int, product: ProductUpdateModel) : Product!
+}

spring-boot-modules/spring-boot-logging-log4j2/pom.xml

@@ -102,6 +102,7 @@
         <!-- used only in dependency management to force this version, not included as a direct dependency -->
         <junit.version>4.13.2</junit.version>
         <junit-jupiter.version>5.8.1</junit-jupiter.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

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

@@ -70,6 +70,7 @@
         <maven.compiler.target>1.8</maven.compiler.target>
         <eclipse.birt.runtime.version>4.8.0</eclipse.birt.runtime.version>
         <log4j.version>1.2.17</log4j.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

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

@@ -11,6 +11,18 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -128,6 +140,7 @@
         <yarn.version>v1.12.1</yarn.version>
         <spring-boot.version>2.4.4</spring-boot.version>
         <javafaker.version>1.0.2</javafaker.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

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

@@ -10,6 +10,7 @@ This module contains articles about Spring Boot Security
 - [Guide to @CurrentSecurityContext in Spring Security](https://www.baeldung.com/spring-currentsecuritycontext)
 - [Disable Security for a Profile in Spring Boot](https://www.baeldung.com/spring-security-disable-profile)
 - [Spring @EnableWebSecurity vs. @EnableGlobalMethodSecurity](https://www.baeldung.com/spring-enablewebsecurity-vs-enableglobalmethodsecurity)
+- [Spring Security – Configuring Different URLs](https://www.baeldung.com/spring-security-configuring-urls)
 
 
 ### Spring Boot Security Auto-Configuration

spring-boot-modules/spring-boot-swagger-keycloak/pom.xml

@@ -24,6 +24,13 @@
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
         </dependencies>
     </dependencyManagement>
 
@@ -62,6 +69,7 @@
         <spring-boot.version>2.4.5</spring-boot.version>
         <springfox.version>3.0.0</springfox.version>
         <keycloak.version>15.0.2</keycloak.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

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

@@ -5,3 +5,4 @@
 - [Generate PDF from Swagger API Documentation](https://www.baeldung.com/swagger-generate-pdf)
 - [Remove Basic Error Controller In SpringFox Swagger-UI](https://www.baeldung.com/spring-swagger-remove-error-controller)
 - [Setting Example and Description with Swagger](https://www.baeldung.com/swagger-set-example-description)
+- [Document Enum in Swagger](https://www.baeldung.com/swagger-enum)

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

@@ -14,6 +14,18 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -131,6 +143,7 @@
         <gmavenplus-plugin.version>1.6</gmavenplus-plugin.version>
         <redis.version>0.7.2</redis.version>
         <spring-boot.version>2.5.0</spring-boot.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-cloud/spring-cloud-contract/pom.xml

@@ -21,6 +21,13 @@
 
     <dependencyManagement>
         <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-starter-web</artifactId>
@@ -55,6 +62,7 @@
     <properties>
         <spring-cloud.version>2.1.1.RELEASE</spring-cloud.version>
         <spring-boot.version>2.1.4.RELEASE</spring-boot.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-cloud/spring-cloud-eureka-self-preservation/pom.xml

@@ -15,6 +15,18 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
     
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <modules>
         <module>spring-cloud-eureka-server</module>
         <module>spring-cloud-eureka-client</module>
@@ -32,6 +44,7 @@
     <properties>
         <spring-boot.version>2.1.3.RELEASE</spring-boot.version>
         <spring-cloud-dependencies.version>Greenwich.SR3</spring-cloud-dependencies.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-cloud/spring-cloud-eureka/pom.xml

@@ -15,6 +15,18 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
     
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <modules>
         <module>spring-cloud-eureka-server</module>
         <module>spring-cloud-eureka-client</module>
@@ -34,6 +46,7 @@
     <properties>
         <spring-boot.version>2.1.2.RELEASE</spring-boot.version>
         <spring-cloud-dependencies.version>Greenwich.RELEASE</spring-cloud-dependencies.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-cloud/spring-cloud-load-balancer/pom.xml

@@ -20,6 +20,18 @@
         <module>spring-cloud-loadbalancer-client</module>
     </modules>
     
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -32,6 +44,7 @@
     <properties>
         <spring-boot.version>2.6.1</spring-boot.version>
         <spring-cloud.version>2021.0.0</spring-cloud.version>
+         <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

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

@@ -4,3 +4,4 @@
 - [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)
 - [Feign Logging Configuration](https://www.baeldung.com/java-feign-logging)
+- [Provide an OAuth2 Token to a Feign Client](https://www.baeldung.com/spring-cloud-feign-oauth-token)

spring-cloud/spring-cloud-stream-starters/twitterhdfs/pom.xml

@@ -78,6 +78,7 @@
         <!-- used only in dependency management to force this version, not included as a direct dependency -->
         <junit.version>4.13.2</junit.version>
         <junit-jupiter.version>5.8.1</junit-jupiter.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-cloud/spring-cloud-zuul-eureka-integration/eureka-client/pom.xml

@@ -17,6 +17,13 @@
 
     <dependencyManagement>
         <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
             <dependency>
                 <groupId>org.springframework.cloud</groupId>
                 <artifactId>spring-cloud-starter-parent</artifactId>
@@ -46,4 +53,8 @@
         </dependency>
     </dependencies>
     
+    <properties>
+        <log4j2.version>2.17.1</log4j2.version>
+    </properties>
+
 </project>

spring-cloud/spring-cloud-zuul-eureka-integration/eureka-server/pom.xml

@@ -17,6 +17,13 @@
 
     <dependencyManagement>
         <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
             <dependency>
                 <groupId>org.springframework.cloud</groupId>
                 <artifactId>spring-cloud-starter-parent</artifactId>
@@ -46,4 +53,8 @@
         </dependency>
     </dependencies>
     
+    <properties>
+        <log4j2.version>2.17.1</log4j2.version>
+    </properties>
+
 </project>

spring-cloud/spring-cloud-zuul-eureka-integration/zuul-server/pom.xml

@@ -14,6 +14,13 @@
 
     <dependencyManagement>
         <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
             <dependency>
                 <groupId>org.springframework.cloud</groupId>
                 <artifactId>spring-cloud-starter-parent</artifactId>
@@ -54,4 +61,8 @@
         </dependency>
     </dependencies>
     
+     <properties>
+        <log4j2.version>2.17.1</log4j2.version>
+    </properties>
+
 </project>

spring-cloud/spring-cloud-zuul/spring-zuul-rate-limiting/pom.xml

@@ -14,6 +14,18 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
     
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <dependencies>
         <dependency>
             <groupId>com.marcosbarbero.cloud</groupId>
@@ -44,6 +56,7 @@
         <rate.limit.version>2.2.0.RELEASE</rate.limit.version>
         <spring-boot.version>2.4.7</spring-boot.version>
         <spring-cloud-dependencies.version>2020.0.4</spring-cloud-dependencies.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-di-2/pom.xml

@@ -16,6 +16,13 @@
 
     <dependencyManagement>
         <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-dependencies</artifactId>
@@ -80,6 +87,7 @@
         <spring-boot.version>2.6.1</spring-boot.version>
         <aspectj-plugin.version>1.11</aspectj-plugin.version>
         <javax.inject.version>1</javax.inject.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-di-3/README.md

@@ -5,4 +5,5 @@ This module contains articles about dependency injection with Spring
 ### Relevant Articles
 
 - [@Lookup Annotation in Spring](https://www.baeldung.com/spring-lookup)
+- [Spring @Autowired Field Null – Common Causes and Solutions](https://www.baeldung.com/spring-autowired-field-null)
 - More articles: [[<-- prev]](../spring-di-2)

spring-di-3/pom.xml

@@ -16,6 +16,13 @@
 
     <dependencyManagement>
         <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-dependencies</artifactId>
@@ -40,6 +47,7 @@
 
     <properties>
         <spring-boot.version>2.6.1</spring-boot.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-native/pom.xml

@@ -75,6 +75,7 @@
         <java.version>1.8</java.version>
         <maven.compiler.target>1.8</maven.compiler.target>
         <maven.compiler.source>1.8</maven.compiler.source>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-roo/pom.xml

@@ -625,6 +625,7 @@
         <bootstrap.ie10-viewport-bug-workaround.version>1.0.3</bootstrap.ie10-viewport-bug-workaround.version>
         <querydsl-processor.version>2.0.0.RELEASE</querydsl-processor.version>
         <olap4j.version>1.2.0</olap4j.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-security-modules/spring-5-security-oauth/pom.xml

@@ -16,6 +16,19 @@
         <relativePath>../../parent-boot-2</relativePath>
     </parent>
     
+     <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+    
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -72,6 +85,7 @@
             is available -->
         <spring-boot.version>2.5.2</spring-boot.version>
         <start-class>com.baeldung.oauth2.SpringOAuthApplication</start-class>
+         <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-security-modules/spring-security-legacy-oidc/pom.xml

@@ -15,6 +15,18 @@
         <relativePath>../../parent-boot-2</relativePath>
     </parent>
     
+     <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -50,6 +62,7 @@
         <spring-security-jwt.version>1.0.9.RELEASE</spring-security-jwt.version>
         <jwks-rsa.version>0.3.0</jwks-rsa.version>
         <spring-boot.version>2.4.7</spring-boot.version>
+         <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-security-modules/spring-security-web-boot-3/src/main/java/com/baeldung/logging/LoggingController.java

@@ -0,0 +1,16 @@
+package com.baeldung.logging;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+
+@Controller
+public class LoggingController {
+
+    @GetMapping("/logging")
+    public ResponseEntity<String> logging() {
+        return new ResponseEntity<>("logging/baeldung", HttpStatus.OK);
+    }
+
+}

spring-security-modules/spring-security-web-boot-3/src/main/java/com/baeldung/logging/SecurityConfig.java

@@ -0,0 +1,26 @@
+package com.baeldung.logging;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.web.builders.WebSecurity;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
+
+@EnableWebSecurity
+public class SecurityConfig extends WebSecurityConfigurerAdapter {
+
+    @Value("${spring.websecurity.debug:false}")
+    boolean webSecurityDebug;
+
+    @Override
+    public void configure(WebSecurity web) {
+        web.debug(webSecurityDebug);
+    }
+
+    @Override
+    protected void configure(HttpSecurity http) throws Exception {
+        http.authorizeRequests()
+            .antMatchers("/**")
+            .permitAll();
+    }
+}

spring-security-modules/spring-security-web-boot-3/src/main/java/com/baeldung/logging/SecurityLoggingApplication.java

@@ -0,0 +1,14 @@
+package com.baeldung.logging;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SecurityLoggingApplication {
+
+    public static void main(String... args) {
+        SpringApplication application = new SpringApplication(SecurityLoggingApplication.class);
+        application.setAdditionalProfiles("logging");
+        application.run(args);
+    }
+}

spring-security-modules/spring-security-web-boot-3/src/main/resources/application-logging.properties

@@ -0,0 +1,4 @@
+
+logging.level.org.springframework.security=DEBUG
+
+spring.websecurity.debug=true

spring-swagger-codegen/custom-validations-opeanpi-codegen/pom.xml

@@ -100,6 +100,7 @@
     <properties>
         <java.version>11</java.version>
         <springfox-version>3.0.0</springfox-version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>

spring-web-modules/spring-boot-jsp/pom.xml

@@ -23,6 +23,13 @@
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>
+            <dependency>
+                <groupId>org.apache.logging.log4j</groupId>
+                <artifactId>log4j-bom</artifactId>
+                <version>${log4j2.version}</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
             <dependency>
                 <groupId>org.springframework.boot</groupId>
                 <artifactId>spring-boot-dependencies</artifactId>
@@ -92,6 +99,7 @@
     <properties>
         <jstl.version>1.2</jstl.version>
         <spring-boot.version>2.4.4</spring-boot.version>
+        <log4j2.version>2.17.1</log4j2.version>
     </properties>
 
 </project>