HandleDelegate did not remove the annotation @Delegate from javac's AST, so HandleDelegate was called multiple times for the same field resulting in an error saying the delegate method was already defined.

Also added a test for @Delegate that uncovered this issue.

src/core/lombok/javac/handlers/HandleDelegate.java

@@ -21,6 +21,8 @@
  */
 package lombok.javac.handlers;
 
+import static lombok.javac.handlers.JavacHandlerUtil.markAnnotationAsProcessed;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -90,6 +92,7 @@ public class HandleDelegate implements JavacAnnotationHandler<Delegate> {
 			"finalize()"));
 	
 	@Override public boolean handle(AnnotationValues<Delegate> annotation, JCAnnotation ast, JavacNode annotationNode) {
+		markAnnotationAsProcessed(annotationNode, Delegate.class);
 		if (annotationNode.up().getKind() != Kind.FIELD) {
 			// As the annotation is legal on fields only, javac itself will take care of printing an error message for this.
 			return false;

test/transform/resource/after-delombok/DelegateTypesAndExcludes.java

@@ -0,0 +1,35 @@
+class DelegatePlain {
+	private final BarImpl bar = new BarImpl();
+	private final FooImpl foo = new FooImpl();
+
+	private static class FooImpl implements Foo {
+		public void foo() {
+		}
+
+		public void bar(java.util.ArrayList<java.lang.String> list) {
+		}
+	}
+
+	private static class BarImpl implements Bar {
+		public void bar(java.util.ArrayList<java.lang.String> list) {
+		}
+	}
+
+	private static interface Foo extends Bar {
+		void foo();
+	}
+
+	private static interface Bar {
+		void bar(java.util.ArrayList<java.lang.String> list);
+	}
+
+	@java.lang.SuppressWarnings("all")
+	public void bar(final java.util.ArrayList<java.lang.String> list) {
+		this.bar.bar(list);
+	}
+
+	@java.lang.SuppressWarnings("all")
+	public void foo() {
+		this.foo.foo();
+	}
+}

test/transform/resource/after-ecj/DelegateTypesAndExcludes.java

@@ -0,0 +1 @@
+//ignore

test/transform/resource/before/DelegateTypesAndExcludes.java

@@ -0,0 +1,28 @@
+import lombok.Delegate;
+class DelegatePlain {
+	@Delegate(types = Bar.class)
+	private final BarImpl bar = new BarImpl();
+	@Delegate(types = Foo.class, excludes = Bar.class)
+	private final FooImpl foo = new FooImpl();
+
+	private static class FooImpl implements Foo {
+		public void foo() {
+		}
+
+		public void bar(java.util.ArrayList<java.lang.String> list) {
+		}
+	}
+
+	private static class BarImpl implements Bar {
+		public void bar(java.util.ArrayList<java.lang.String> list) {
+		}
+	}
+
+	private static interface Foo extends Bar {
+		void foo();
+	}
+
+	private static interface Bar {
+		void bar(java.util.ArrayList<java.lang.String> list);
+	}
+}