AndreasIgel · Oct 12, 2026 · Oct 11, 2026 · Oct 11, 2026 · Oct 11, 2026 · Oct 11, 2026
diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
@@ -71,6 +71,9 @@ jobs:
     - name: Build with Maven
       run: mvn -B install -Pmetrics --file pom.xml
 
+    - name: License header check (incl. performance-test)
+      run: mvn -B license:check -Pperformance-test --file pom.xml
+
     - name: Verify committed generated example builders
       if: github.event_name == 'pull_request'
       run: |

diff --git a/LICENSE.txt b/LICENSE.txt
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2026 Andreas Igel
+Copyright (c) 2025-2026 Andreas Igel
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

diff --git a/core/pom.xml b/core/pom.xml
@@ -75,6 +75,7 @@
     <plugin.central.publishing.version>0.11.0</plugin.central.publishing.version>
     <plugin.cyclonedx.version>2.9.3</plugin.cyclonedx.version>
     <plugin.code-format.version>2.29</plugin.code-format.version>
+    <plugin.license.version>5.1.2</plugin.license.version>
     <plugin.maven.compiler.version>3.16.0</plugin.maven.compiler.version>
     <plugin.maven.source.version>3.4.0</plugin.maven.source.version>
     <plugin.maven.javadoc.version>3.12.0</plugin.maven.javadoc.version>
@@ -123,6 +124,35 @@
         </executions>
       </plugin>
 
+      <!-- License Header Check -->
+      <plugin>
+        <groupId>com.mycila</groupId>
+        <artifactId>license-maven-plugin</artifactId>
+        <version>${plugin.license.version}</version>
+        <configuration>
+          <licenseSets>
+            <licenseSet>
+              <header>${maven.multiModuleProjectDirectory}/LICENSE.txt</header>
+              <includes>
+                <include>src/main/java/**</include>
+                <include>src/test/java/**</include>
+              </includes>
+              <excludes>
+                <exclude>generated-example-builder/**</exclude>
+                <exclude>target/**</exclude>
+              </excludes>
+            </licenseSet>
+          </licenseSets>
+        </configuration>
+        <executions>
+          <execution>
+            <goals>
+              <goal>check</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+
       <!-- Compiler Plugin -->
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>

diff --git a/...src/main/java/org/javahelpers/simple/builders/core/annotations/BuilderImplementation.java b/...src/main/java/org/javahelpers/simple/builders/core/annotations/BuilderImplementation.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/annotations/Default.java b/core/src/main/java/org/javahelpers/simple/builders/core/annotations/Default.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/.../main/java/org/javahelpers/simple/builders/core/annotations/Ignore4BuilderGeneration.java b/.../main/java/org/javahelpers/simple/builders/core/annotations/Ignore4BuilderGeneration.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/annotations/IgnoreInBuilder.java b/core/src/main/java/org/javahelpers/simple/builders/core/annotations/IgnoreInBuilder.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/annotations/SimpleBuilder.java b/core/src/main/java/org/javahelpers/simple/builders/core/annotations/SimpleBuilder.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/.../main/java/org/javahelpers/simple/builders/core/annotations/SimpleBuilderConstructor.java b/.../main/java/org/javahelpers/simple/builders/core/annotations/SimpleBuilderConstructor.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/annotations/SimpleBuilderFor.java b/core/src/main/java/org/javahelpers/simple/builders/core/annotations/SimpleBuilderFor.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/annotations/SimpleBuilderFors.java b/core/src/main/java/org/javahelpers/simple/builders/core/annotations/SimpleBuilderFors.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/.../src/main/java/org/javahelpers/simple/builders/core/annotations/SimpleMinimalBuilder.java b/.../src/main/java/org/javahelpers/simple/builders/core/annotations/SimpleMinimalBuilder.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/builders/ArrayListBuilder.java b/core/src/main/java/org/javahelpers/simple/builders/core/builders/ArrayListBuilder.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/...va/org/javahelpers/simple/builders/core/builders/ArrayListBuilderWithElementBuilders.java b/...va/org/javahelpers/simple/builders/core/builders/ArrayListBuilderWithElementBuilders.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/builders/HashMapBuilder.java b/core/src/main/java/org/javahelpers/simple/builders/core/builders/HashMapBuilder.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/builders/HashSetBuilder.java b/core/src/main/java/org/javahelpers/simple/builders/core/builders/HashSetBuilder.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/...java/org/javahelpers/simple/builders/core/builders/HashSetBuilderWithElementBuilders.java b/...java/org/javahelpers/simple/builders/core/builders/HashSetBuilderWithElementBuilders.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/enums/AccessModifier.java b/core/src/main/java/org/javahelpers/simple/builders/core/enums/AccessModifier.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/enums/FormattingMode.java b/core/src/main/java/org/javahelpers/simple/builders/core/enums/FormattingMode.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -13,7 +13,7 @@
  * The above copyright notice and this permission notice shall be included in all
  * copies or substantial portions of the Software.
  *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT ANY KIND, EXPRESS OR
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/enums/OptionState.java b/core/src/main/java/org/javahelpers/simple/builders/core/enums/OptionState.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/interfaces/IBuilderBase.java b/core/src/main/java/org/javahelpers/simple/builders/core/interfaces/IBuilderBase.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/util/BuilderToStringStyle.java b/core/src/main/java/org/javahelpers/simple/builders/core/util/BuilderToStringStyle.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/main/java/org/javahelpers/simple/builders/core/util/TrackedValue.java b/core/src/main/java/org/javahelpers/simple/builders/core/util/TrackedValue.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/test/java/org/javahelpers/simple/builders/core/builders/ArrayListBuilderTest.java b/core/src/test/java/org/javahelpers/simple/builders/core/builders/ArrayListBuilderTest.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/...rg/javahelpers/simple/builders/core/builders/ArrayListBuilderWithElementBuildersTest.java b/...rg/javahelpers/simple/builders/core/builders/ArrayListBuilderWithElementBuildersTest.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/test/java/org/javahelpers/simple/builders/core/builders/HashMapBuilderTest.java b/core/src/test/java/org/javahelpers/simple/builders/core/builders/HashMapBuilderTest.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/test/java/org/javahelpers/simple/builders/core/builders/HashSetBuilderTest.java b/core/src/test/java/org/javahelpers/simple/builders/core/builders/HashSetBuilderTest.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/.../org/javahelpers/simple/builders/core/builders/HashSetBuilderWithElementBuildersTest.java b/.../org/javahelpers/simple/builders/core/builders/HashSetBuilderWithElementBuildersTest.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/test/java/org/javahelpers/simple/builders/core/util/BuilderToStringStyleTest.java b/core/src/test/java/org/javahelpers/simple/builders/core/util/BuilderToStringStyleTest.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/core/src/test/java/org/javahelpers/simple/builders/core/util/TrackedValueTest.java b/core/src/test/java/org/javahelpers/simple/builders/core/util/TrackedValueTest.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

diff --git a/docs/CONTRIBUTING.md b/docs/CONTRIBUTING.md
@@ -297,6 +297,20 @@ mvn fmt:format
 mvn fmt:check
 ```
 
+### License Headers
+
+All Java source files must carry the MIT license header defined in
+[`LICENSE.txt`](../LICENSE.txt). The `license-maven-plugin` verifies it
+during `mvn verify`:
+
+```bash
+# Check headers
+mvn license:check
+
+# Add or fix headers automatically
+mvn license:format
+```
+
 ### Code Quality
 
 - **SonarLint**: We use SonarQube rules. Install the SonarLint IDE plugin for real-time feedback.

diff --git a/example-custom-generator/pom.xml b/example-custom-generator/pom.xml
@@ -18,6 +18,7 @@
     <commons-lang.version>3.21.0</commons-lang.version>
 
     <plugin.maven.compiler.version>3.16.0</plugin.maven.compiler.version>
+    <plugin.license.version>5.1.2</plugin.license.version>
     <maven.compiler.source>${java.version}</maven.compiler.source>
     <maven.compiler.target>${java.version}</maven.compiler.target>
     <maven.compiler.release>${java.version}</maven.compiler.release>
@@ -40,6 +41,35 @@
 
   <build>
     <plugins>
+      <!-- License Header Check -->
+      <plugin>
+        <groupId>com.mycila</groupId>
+        <artifactId>license-maven-plugin</artifactId>
+        <version>${plugin.license.version}</version>
+        <configuration>
+          <licenseSets>
+            <licenseSet>
+              <header>${maven.multiModuleProjectDirectory}/LICENSE.txt</header>
+              <includes>
+                <include>src/main/java/**</include>
+                <include>src/test/java/**</include>
+              </includes>
+              <excludes>
+                <exclude>generated-example-builder/**</exclude>
+                <exclude>target/**</exclude>
+              </excludes>
+            </licenseSet>
+          </licenseSets>
+        </configuration>
+        <executions>
+          <execution>
+            <goals>
+              <goal>check</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>

diff --git a/...c/main/java/org/javahelpers/simple/builders/example/custom/StringValidationGenerator.java b/...c/main/java/org/javahelpers/simple/builders/example/custom/StringValidationGenerator.java
@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2026 Andreas Igel
+ * Copyright (c) 2025-2026 Andreas Igel
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal