fix: pmd warnings

src/main/java/com/sitepark/ies/contentrepository/core/domain/entity/Identifier.java

@@ -7,6 +7,10 @@
 
 public final class Identifier {
 
+	private static final int MAX_ID_LENGTH = 19;
+
+	private static final String ZERO_ID = "0";
+
 	private final Long id;
 
 	private final Anchor anchor;
@@ -48,12 +52,12 @@ public Optional<Anchor> getAnchor() {
 
 	public static boolean isId(String str) {
 
-		if (str.equals("0")) {
+		if (ZERO_ID.equals(str)) {
 			throw new IllegalArgumentException("id should be greater than 0");
 		}
 
 		int length = str.length();
-		if (length > 19) {
+		if (length > MAX_ID_LENGTH) {
 			return false;
 		}
 

src/main/java/com/sitepark/ies/contentrepository/core/domain/entity/MediaReference.java

@@ -71,17 +71,13 @@ protected Builder(MediaReference media) {
 		}
 
 		public Builder mediaId(String mediaId) {
-			if (mediaId == null) {
-				throw new NullPointerException("mediaId is null");
-			}
+			Objects.requireNonNull(mediaId, "mediaId is null");
 			this.mediaId = mediaId;
 			return this;
 		}
 
 		public Builder usedBy(String usedBy) {
-			if (usedBy == null) {
-				throw new NullPointerException("usedBy is null");
-			}
+			Objects.requireNonNull(usedBy, "usedBy is null");
 			this.usedBy = usedBy;
 			return this;
 		}

src/main/java/com/sitepark/ies/contentrepository/core/domain/entity/query/CursorBasedQuery.java

@@ -51,7 +51,9 @@ public final boolean equals(Object o) {
 	}
 
 	/**
-	 * @see <a href="https://www.artima.com/articles/how-to-write-an-equality-method-in-java">How to Write an Equality Method in Java</a>
+	 * @see <a href="https://www.artima.com/articles/how-to-write-an-equality-method-in-java">
+	 * 	How to Write an Equality Method in Java
+	 * </a>
 	 */
 	@Override
 	public boolean canEqual(Object other) {

src/main/java/com/sitepark/ies/contentrepository/core/domain/entity/query/Query.java

@@ -60,7 +60,9 @@ public boolean equals(Object o) {
 	}
 
 	/**
-	 * @see <a href="https://www.artima.com/articles/how-to-write-an-equality-method-in-java">How to Write an Equality Method in Java</a>
+	 * @see <a href="https://www.artima.com/articles/how-to-write-an-equality-method-in-java">
+	 * 	How to Write an Equality Method in Java
+	 * </a>
 	 */
 	public boolean canEqual(Object other) {
 		return (other instanceof Query);

src/main/java/com/sitepark/ies/contentrepository/core/domain/entity/query/SubTreeQuery.java

@@ -46,7 +46,9 @@ public final boolean equals(Object o) {
 	}
 
 	/**
-	 * @see <a href="https://www.artima.com/articles/how-to-write-an-equality-method-in-java">How to Write an Equality Method in Java</a>
+	 * @see <a href="https://www.artima.com/articles/how-to-write-an-equality-method-in-java">
+	 * 	How to Write an Equality Method in Java
+	 * </a>
 	 */
 	@Override
 	public boolean canEqual(Object other) {

src/test/java/com/sitepark/ies/contentrepository/core/domain/entity/EntityBulkExecutionTest.java

@@ -16,6 +16,7 @@
 
 import nl.jqno.equalsverifier.EqualsVerifier;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class EntityBulkExecutionTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/entity/EntityLockTest.java

@@ -13,6 +13,7 @@
 
 import nl.jqno.equalsverifier.EqualsVerifier;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class EntityLockTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/entity/HistoryEntryTest.java

@@ -11,6 +11,7 @@
 
 import nl.jqno.equalsverifier.EqualsVerifier;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class HistoryEntryTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/entity/IdentifierTest.java

@@ -9,6 +9,7 @@
 
 import nl.jqno.equalsverifier.EqualsVerifier;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class IdentifierTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/entity/MediaReferenceTest.java

@@ -7,6 +7,7 @@
 
 import nl.jqno.equalsverifier.EqualsVerifier;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class MediaReferenceTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/entity/RecycleBinItemTest.java

@@ -14,6 +14,7 @@
 
 import nl.jqno.equalsverifier.EqualsVerifier;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class RecycleBinItemTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/entity/filter/FilterTest.java

@@ -19,6 +19,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.sitepark.ies.contentrepository.core.domain.databind.DatabindModule;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class FilterTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/entity/query/CursorBasedQueryTest.java

@@ -6,6 +6,7 @@
 
 import nl.jqno.equalsverifier.EqualsVerifier;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class CursorBasedQueryTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/exception/EntityNotFoundExceptionTest.java

@@ -5,6 +5,7 @@
 
 import org.junit.jupiter.api.Test;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class EntityNotFoundExceptionTest {
 
 	@Test

src/test/java/com/sitepark/ies/contentrepository/core/domain/exception/GroupNotEmptyExceptionTest.java

@@ -5,6 +5,7 @@
 
 import org.junit.jupiter.api.Test;
 
+@SuppressWarnings("PMD.AvoidDuplicateLiterals")
 class GroupNotEmptyExceptionTest {
 
 	@Test