From 58db5a11b76fde5e6121a8a4127a61991a9956b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Michael?= <b.michael@gmx.de>
Date: Fri, 9 May 2025 14:24:05 +0200
Subject: [PATCH 1/2] [Fix 3880] Use AssertionError with @UtilityClass

---
 src/core/lombok/bytecode/AsmUtil.java                |  2 +-
 src/core/lombok/eclipse/handlers/HandleLog.java      |  2 +-
 .../lombok/eclipse/handlers/HandleUtilityClass.java  | 12 ++++++------
 src/core/lombok/experimental/UtilityClass.java       |  2 +-
 src/core/lombok/javac/handlers/HandleLog.java        |  2 +-
 .../lombok/javac/handlers/HandleUtilityClass.java    |  2 +-
 .../resource/after-delombok/UtilityClass.java        |  8 ++++----
 .../resource/after-delombok/UtilityClassGeneric.java |  2 +-
 .../resource/after-delombok/UtilityClassInner.java   |  2 +-
 test/transform/resource/after-ecj/UtilityClass.java  |  8 ++++----
 .../resource/after-ecj/UtilityClassGeneric.java      |  2 +-
 .../resource/after-ecj/UtilityClassInner.java        |  2 +-
 .../experimental/UtilityClassExample_post.jpage      |  2 +-
 13 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/src/core/lombok/bytecode/AsmUtil.java b/src/core/lombok/bytecode/AsmUtil.java
index fc2533e5d8..f3dcdec4f8 100644
--- a/src/core/lombok/bytecode/AsmUtil.java
+++ b/src/core/lombok/bytecode/AsmUtil.java
@@ -30,7 +30,7 @@
 
 class AsmUtil {
 	private AsmUtil() {
-		throw new UnsupportedOperationException();
+		throw new AssertionError();
 	}
 	
 	static byte[] fixJSRInlining(byte[] byteCode) {
diff --git a/src/core/lombok/eclipse/handlers/HandleLog.java b/src/core/lombok/eclipse/handlers/HandleLog.java
index 2bbc300a8b..5368b705d4 100644
--- a/src/core/lombok/eclipse/handlers/HandleLog.java
+++ b/src/core/lombok/eclipse/handlers/HandleLog.java
@@ -54,7 +54,7 @@ public class HandleLog {
 	private static final IdentifierName LOG = IdentifierName.valueOf("log");
 	
 	private HandleLog() {
-		throw new UnsupportedOperationException();
+		throw new AssertionError();
 	}
 	
 	public static void processAnnotation(LoggingFramework framework, AnnotationValues<? extends java.lang.annotation.Annotation> annotation, Annotation source, EclipseNode annotationNode) {
diff --git a/src/core/lombok/eclipse/handlers/HandleUtilityClass.java b/src/core/lombok/eclipse/handlers/HandleUtilityClass.java
index 9a18b20bdd..2cc31ed629 100644
--- a/src/core/lombok/eclipse/handlers/HandleUtilityClass.java
+++ b/src/core/lombok/eclipse/handlers/HandleUtilityClass.java
@@ -141,11 +141,11 @@ private void changeModifiersAndGenerateConstructor(EclipseNode typeNode, Eclipse
 		if (requiresClInit && !alreadyHasClinit) classDecl.addClinit();
 	}
 	
-	private static final char[][] JAVA_LANG_UNSUPPORTED_OPERATION_EXCEPTION = new char[][] {
-		TypeConstants.JAVA, TypeConstants.LANG, "UnsupportedOperationException".toCharArray()
+	private static final char[][] JAVA_LANG_ASSERTION_ERROR = new char[][] {
+		TypeConstants.JAVA, TypeConstants.LANG, "AssertionError".toCharArray()
 	};
 	
-	private static final char[] UNSUPPORTED_MESSAGE = "This is a utility class and cannot be instantiated".toCharArray();
+	private static final char[] ERROR_MESSAGE = "This is a utility class and cannot be instantiated".toCharArray();
 	
 	private void createPrivateDefaultConstructor(EclipseNode typeNode, EclipseNode sourceNode) {
 		ASTNode source = sourceNode.get();
@@ -162,11 +162,11 @@ private void createPrivateDefaultConstructor(EclipseNode typeNode, EclipseNode s
 		constructor.bits |= ECLIPSE_DO_NOT_TOUCH_FLAG;
 		constructor.arguments = null;
 		
-		long[] ps = new long[JAVA_LANG_UNSUPPORTED_OPERATION_EXCEPTION.length];
+		long[] ps = new long[JAVA_LANG_ASSERTION_ERROR.length];
 		AllocationExpression exception = new AllocationExpression();
-		exception.type = new QualifiedTypeReference(JAVA_LANG_UNSUPPORTED_OPERATION_EXCEPTION, ps);
+		exception.type = new QualifiedTypeReference(JAVA_LANG_ASSERTION_ERROR, ps);
 		exception.arguments = new Expression[] {
-				new StringLiteral(UNSUPPORTED_MESSAGE, 0, 0, 0)
+				new StringLiteral(ERROR_MESSAGE, 0, 0, 0)
 		};
 		ThrowStatement throwStatement = new ThrowStatement(exception, 0, 0);
 		
diff --git a/src/core/lombok/experimental/UtilityClass.java b/src/core/lombok/experimental/UtilityClass.java
index f828166056..aaa1d30748 100644
--- a/src/core/lombok/experimental/UtilityClass.java
+++ b/src/core/lombok/experimental/UtilityClass.java
@@ -31,7 +31,7 @@
  * 
  * If a class is annotated with {@code @UtilityClass}, the following things happen to it:<ul>
  * <li>It is marked final.</li>
- * <li>If any constructors are declared in it, an error is generated. Otherwise, a private no-args constructor is generated; it throws a {@code UnsupportedOperationException}.</li>
+ * <li>If any constructors are declared in it, an error is generated. Otherwise, a private no-args constructor is generated; it throws a {@code AssertionError}.</li>
  * <li>All methods, inner classes, and fields in the class are marked static.</li>
  * <li><em>WARNING:</em> Do not use non-star static imports to import these members; javac won't be able to figure it out. Use either:
  *    <code>import static ThisType.*;</code> or don't static-import.</li>
diff --git a/src/core/lombok/javac/handlers/HandleLog.java b/src/core/lombok/javac/handlers/HandleLog.java
index 7484ae661b..7f05558dce 100644
--- a/src/core/lombok/javac/handlers/HandleLog.java
+++ b/src/core/lombok/javac/handlers/HandleLog.java
@@ -52,7 +52,7 @@ public class HandleLog {
 	private static final IdentifierName LOG = IdentifierName.valueOf("log");
 	
 	private HandleLog() {
-		throw new UnsupportedOperationException();
+		throw new AssertionError();
 	}
 	
 	public static void processAnnotation(LoggingFramework framework, AnnotationValues<?> annotation, JavacNode annotationNode) {
diff --git a/src/core/lombok/javac/handlers/HandleUtilityClass.java b/src/core/lombok/javac/handlers/HandleUtilityClass.java
index bc171b8f89..f7d6148dcd 100644
--- a/src/core/lombok/javac/handlers/HandleUtilityClass.java
+++ b/src/core/lombok/javac/handlers/HandleUtilityClass.java
@@ -154,7 +154,7 @@ private void createPrivateDefaultConstructor(JavacNode typeNode) {
 	}
 	
 	private List<JCStatement> createThrowStatement(JavacNode typeNode, JavacTreeMaker maker) {
-		JCExpression exceptionType = genJavaLangTypeRef(typeNode, "UnsupportedOperationException");
+		JCExpression exceptionType = genJavaLangTypeRef(typeNode, "AssertionError");
 		List<JCExpression> jceBlank = List.nil();
 		JCExpression message = maker.Literal("This is a utility class and cannot be instantiated");
 		JCExpression exceptionInstance = maker.NewClass(null, jceBlank, exceptionType, List.of(message), null);
diff --git a/test/transform/resource/after-delombok/UtilityClass.java b/test/transform/resource/after-delombok/UtilityClass.java
index 983fbc29c3..0177f71d83 100644
--- a/test/transform/resource/after-delombok/UtilityClass.java
+++ b/test/transform/resource/after-delombok/UtilityClass.java
@@ -14,7 +14,7 @@ protected static class InnerStaticClass {
 	@java.lang.SuppressWarnings("all")
 	@lombok.Generated
 	private UtilityClass() {
-		throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+		throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
 	}
 }
 class UtilityInner {
@@ -24,7 +24,7 @@ static final class InnerInnerInner {
 			@java.lang.SuppressWarnings("all")
 			@lombok.Generated
 			private InnerInnerInner() {
-				throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+				throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
 			}
 		}
 	}
@@ -35,7 +35,7 @@ static final class InsideEnum {
 			@java.lang.SuppressWarnings("all")
 			@lombok.Generated
 			private InsideEnum() {
-				throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+				throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
 			}
 		}
 	}
@@ -45,7 +45,7 @@ final class InsideInterface {
 			@java.lang.SuppressWarnings("all")
 			@lombok.Generated
 			private InsideInterface() {
-				throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+				throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
 			}
 		}
 	}
diff --git a/test/transform/resource/after-delombok/UtilityClassGeneric.java b/test/transform/resource/after-delombok/UtilityClassGeneric.java
index 82bd1630a8..2e95a62b57 100644
--- a/test/transform/resource/after-delombok/UtilityClassGeneric.java
+++ b/test/transform/resource/after-delombok/UtilityClassGeneric.java
@@ -13,6 +13,6 @@ static class DTO {
 	@java.lang.SuppressWarnings("all")
 	@lombok.Generated
 	private UtilityClassGeneric() {
-		throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+		throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
 	}
 }
diff --git a/test/transform/resource/after-delombok/UtilityClassInner.java b/test/transform/resource/after-delombok/UtilityClassInner.java
index cd91bc2d7c..5eb36fcd05 100644
--- a/test/transform/resource/after-delombok/UtilityClassInner.java
+++ b/test/transform/resource/after-delombok/UtilityClassInner.java
@@ -4,7 +4,7 @@ static final class UtilClass implements java.io.Serializable {
 		@java.lang.SuppressWarnings("all")
 		@lombok.Generated
 		private UtilClass() {
-			throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+			throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
 		}
 	}
 }
diff --git a/test/transform/resource/after-ecj/UtilityClass.java b/test/transform/resource/after-ecj/UtilityClass.java
index db83c53c97..0413edfe8b 100644
--- a/test/transform/resource/after-ecj/UtilityClass.java
+++ b/test/transform/resource/after-ecj/UtilityClass.java
@@ -21,7 +21,7 @@ static void someMethod() {
   }
   private @java.lang.SuppressWarnings("all") @lombok.Generated UtilityClass() {
     super();
-    throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
   }
 }
 class UtilityInner {
@@ -32,7 +32,7 @@ static class InnerInner {
       }
       private @java.lang.SuppressWarnings("all") @lombok.Generated InnerInnerInner() {
         super();
-        throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+        throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
       }
     }
     InnerInner() {
@@ -46,7 +46,7 @@ enum UtilityInsideEnum {
       }
       private @java.lang.SuppressWarnings("all") @lombok.Generated InsideEnum() {
         super();
-        throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+        throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
       }
     }
     FOO(),
@@ -64,7 +64,7 @@ interface UtilityInsideInterface {
       }
       private @java.lang.SuppressWarnings("all") @lombok.Generated InsideInterface() {
         super();
-        throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+        throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
       }
     }
   }
diff --git a/test/transform/resource/after-ecj/UtilityClassGeneric.java b/test/transform/resource/after-ecj/UtilityClassGeneric.java
index d339a5faa7..f264a61ffd 100644
--- a/test/transform/resource/after-ecj/UtilityClassGeneric.java
+++ b/test/transform/resource/after-ecj/UtilityClassGeneric.java
@@ -16,6 +16,6 @@ static Object convert(DTO dto) {
   }
   private @java.lang.SuppressWarnings("all") @lombok.Generated UtilityClassGeneric() {
     super();
-    throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
   }
 }
diff --git a/test/transform/resource/after-ecj/UtilityClassInner.java b/test/transform/resource/after-ecj/UtilityClassInner.java
index 31bd396c41..ee8620319d 100644
--- a/test/transform/resource/after-ecj/UtilityClassInner.java
+++ b/test/transform/resource/after-ecj/UtilityClassInner.java
@@ -2,7 +2,7 @@
   static final @lombok.experimental.UtilityClass class UtilClass implements java.io.Serializable {
     private @java.lang.SuppressWarnings("all") @lombok.Generated UtilClass() {
       super();
-      throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+      throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
     }
   }
   UtilityClassInner() {
diff --git a/website/usageExamples/experimental/UtilityClassExample_post.jpage b/website/usageExamples/experimental/UtilityClassExample_post.jpage
index ad6cf58322..4cc5b552ad 100644
--- a/website/usageExamples/experimental/UtilityClassExample_post.jpage
+++ b/website/usageExamples/experimental/UtilityClassExample_post.jpage
@@ -2,7 +2,7 @@ public final class UtilityClassExample {
 	private static final int CONSTANT = 5;
 
 	private UtilityClassExample() {
-		throw new java.lang.UnsupportedOperationException("This is a utility class and cannot be instantiated");
+		throw new java.lang.AssertionError("This is a utility class and cannot be instantiated");
 	}
 
 	public static int addSomething(int in) {

From 998be4a9f41725d6150ed65f9968721df9d35342 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Michael?= <b.michael@gmx.de>
Date: Fri, 9 May 2025 14:35:54 +0200
Subject: [PATCH 2/2] Mention me as author

---
 AUTHORS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/AUTHORS b/AUTHORS
index d83703dead..fc2b09257f 100755
--- a/AUTHORS
+++ b/AUTHORS
@@ -5,6 +5,7 @@ Aleksandr Zhelezniak <lekan1992@gmail.com>
 Amine Touzani <ttzn.dev@gmail.com>
 Andre Brait <andrebrait@gmail.com>
 Anshuman Mishra <a.mishra@uber.com>
+Björn Michael <b.michael@gmx.de>
 Bulgakov Alexander <buls@yandex.ru>
 Caleb Brinkman <floralvikings@gmail.com>
 Christian Nüssgens <christian@nuessgens.com>