Bump baseline to Java 21

README.md

@@ -17,7 +17,7 @@ It provides all necessary resources for a Java project to enforce this coding st
 - [SpotBugs](https://spotbugs.github.io)
 - [Error Prone](https://errorprone.info)
 
-❗This project requires a JDK version of 17 or higher.❗  
+❗This project requires a JDK version of 21 or higher.❗  
 
 Moreover, this project provides some sample classes that already use this style guide. 
 These classes can be used as such but are not required in this project. 
@@ -54,4 +54,4 @@ Source code (snippets, examples, and classes) are using the [MIT license](https:
 
 [![License: MIT](https://img.shields.io/badge/license-MIT-yellow.svg)](https://en.wikipedia.org/wiki/MIT_License)
 [![License: CC BY 4.0](https://img.shields.io/badge/License-CC%20BY%204.0-lightgrey.svg)](https://creativecommons.org/licenses/by/4.0/)
-![JDK17](https://img.shields.io/badge/jdk-17-blue.svg)
+![JDK21](https://img.shields.io/badge/jdk-21-blue.svg)

pom.xml

@@ -4,7 +4,7 @@
 
   <groupId>edu.hm.hafner</groupId>
   <artifactId>codingstyle</artifactId>
-  <version>5.26.0-SNAPSHOT</version>
+  <version>6.0.0-SNAPSHOT</version>
   <packaging>jar</packaging>
 
   <name>Java coding style</name>
@@ -47,7 +47,7 @@
   <properties>
     <source.encoding>UTF-8</source.encoding>
     <project.build.sourceEncoding>${source.encoding}</project.build.sourceEncoding>
-    <java.version>17</java.version>
+    <java.version>21</java.version>
     <java.jdk.version>21</java.jdk.version>
 
     <module.name>${project.groupId}.codingstyle</module.name>
@@ -360,7 +360,7 @@
               <recipe>org.openrewrite.staticanalysis.CodeCleanup</recipe>
               <recipe>org.openrewrite.staticanalysis.CommonStaticAnalysis</recipe>
               <recipe>org.openrewrite.staticanalysis.RemoveExtraSemicolons</recipe>
-              <recipe>org.openrewrite.java.migrate.UpgradeToJava17</recipe>
+              <recipe>org.openrewrite.java.migrate.UpgradeToJava21</recipe>
               <recipe>org.openrewrite.java.migrate.util.SequencedCollection</recipe>
               <recipe>org.openrewrite.java.migrate.lang.var.UseVarForObject</recipe>
               <recipe>org.openrewrite.java.migrate.net.JavaNetAPIs</recipe>

src/main/java/edu/hm/hafner/util/FilteredLog.java

@@ -23,18 +23,18 @@
  */
 public class FilteredLog implements Serializable {
     @Serial
-    private static final long serialVersionUID = -8552323621953159904L;
+    private static final long serialVersionUID = 6956036398485594488L;
 
     private static final int DEFAULT_MAX_LINES = 20;
 
     private final String title;
     private final int maxLines;
     private int lines;
 
-    @SuppressWarnings("serial")
-    private final List<String> infoMessages = new ArrayList<>();
-    @SuppressWarnings("serial")
-    private final List<String> errorMessages = new ArrayList<>();
+    @SuppressWarnings("PMD.LooseCoupling")
+    private final ArrayList<String> infoMessages = new ArrayList<>();
+    @SuppressWarnings("PMD.LooseCoupling")
+    private final ArrayList<String> errorMessages = new ArrayList<>();
 
     private transient ReentrantLock lock = new ReentrantLock();
 

src/main/java/edu/hm/hafner/util/Generated.java

@@ -8,13 +8,11 @@
 
 /**
  * This annotation is used to mark source code that has been generated or is somehow not relevant for style checking or
- * code coverage analysis. It is quite similar to the JSR305 annotation. The
- * main difference is that it has class retention, so it is available for tools that work on bytecode (like JaCoCo,
- * PIT, or SpotBugs).
+ * code coverage analysis. It is quite similar to the annotation of the abandoned JSR305 project. The main difference is
+ * that it has class retention, so it is available for tools that work on bytecode (like JaCoCo, PIT, or SpotBugs).
  */
 @Retention(CLASS)
-@Target({PACKAGE, TYPE, ANNOTATION_TYPE, METHOD, CONSTRUCTOR, FIELD,
-        LOCAL_VARIABLE, PARAMETER})
+@Target({PACKAGE, TYPE, ANNOTATION_TYPE, METHOD, CONSTRUCTOR, FIELD, LOCAL_VARIABLE, PARAMETER})
 public @interface Generated {
     /**
      * An optional property that identifies the code generator.

src/test/java/edu/hm/hafner/util/EnsureTest.java

@@ -29,7 +29,7 @@ void shouldNotThrowExceptionIfContractIsValid() {
             Ensure.that("").isNotNull();
             Ensure.that("", "").isNotNull();
             Ensure.that(null, (Object) null).isNull();
-            Ensure.that(new String[] {""}).isNotEmpty();
+            Ensure.that(new String[]{""}).isNotEmpty();
             Ensure.that(SOME_STRING).isNotEmpty();
             Ensure.that(SOME_STRING).isNotBlank();
             Ensure.that("").isInstanceOf(String.class);
@@ -116,7 +116,7 @@ void shouldThrowExceptionIfEmpty() {
                 Ensure.that(Lists.newArrayList("", null, "")).isNotEmpty(ERROR_MESSAGE)).isInstanceOf(
                 AssertionError.class);
         assertThatThrownBy(() ->
-                Ensure.that(new String[] {"", null, ""}).isNotEmpty(ERROR_MESSAGE)).isInstanceOf(AssertionError.class);
+                Ensure.that(new String[]{"", null, ""}).isNotEmpty(ERROR_MESSAGE)).isInstanceOf(AssertionError.class);
         assertThatThrownBy(() ->
                 Ensure.that("").isNotEmpty(ERROR_MESSAGE)).isInstanceOf(AssertionError.class);
         assertThatThrownBy(() ->
@@ -128,7 +128,7 @@ void shouldThrowExceptionIfEmpty() {
         assertThatThrownBy(() ->
                 Ensure.that(Lists.newArrayList("", null, "")).isNotEmpty()).isInstanceOf(AssertionError.class);
         assertThatThrownBy(() ->
-                Ensure.that(new String[] {"", null, ""}).isNotEmpty()).isInstanceOf(AssertionError.class);
+                Ensure.that(new String[]{"", null, ""}).isNotEmpty()).isInstanceOf(AssertionError.class);
         assertThatThrownBy(() ->
                 Ensure.that("").isNotEmpty()).isInstanceOf(AssertionError.class);
         assertThatThrownBy(() ->

src/test/java/edu/hm/hafner/util/LineRangeListTest.java

@@ -1,9 +1,9 @@
 package edu.hm.hafner.util;
 
-import java.util.List;
-
 import org.junit.jupiter.api.Test;
 
+import java.util.List;
+
 import static org.assertj.core.api.Assertions.*;
 
 /**
@@ -43,17 +43,17 @@ void shouldSupportSetOperations() {
         var range = new LineRange(1, 2);
         list.add(range);
 
-        assertThat(list.get(0)).isEqualTo(range);
-        assertThat(list.get(0)).isNotSameAs(range);
+        assertThat(list.getFirst()).isEqualTo(range);
+        assertThat(list.getFirst()).isNotSameAs(range);
         assertThat(list).hasSize(1);
 
         var other = new LineRange(3, 4);
         assertThat(list.set(0, other)).isEqualTo(range);
-        assertThat(list.get(0)).isEqualTo(other);
-        assertThat(list.get(0)).isNotSameAs(other);
+        assertThat(list.getFirst()).isEqualTo(other);
+        assertThat(list.getFirst()).isNotSameAs(other);
         assertThat(list).hasSize(1);
 
-        assertThat(list.remove(0)).isEqualTo(other);
+        assertThat(list.removeFirst()).isEqualTo(other);
         assertThat(list).hasSize(0);
     }