Issue 559: NullPointerException when @nonnull is used in abstract method

- Prevent NPE in javac and give a proper warning in both eclipse and javac
- Add test cases

src/core/lombok/eclipse/handlers/NonNullHandler.java

@@ -82,6 +82,11 @@ public class NonNullHandler extends EclipseAnnotationHandler<NonNull> {
 
 		if (isGenerated(declaration)) return;
 
+		if (declaration.isAbstract()) {
+			annotationNode.addWarning("@NonNull is meaningless on a parameter of an abstract method.");
+			return;
+		}
+
 		// Possibly, if 'declaration instanceof ConstructorDeclaration', fetch declaration.constructorCall, search it for any references to our parameter,
 		// and if they exist, create a new method in the class: 'private static <T> T lombok$nullCheck(T expr, String msg) {if (expr == null) throw NPE; return expr;}' and
 		// wrap all references to it in the super/this to a call to this method.

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

@@ -76,6 +76,11 @@ public class NonNullHandler extends JavacAnnotationHandler<NonNull> {
 
 		if (JavacHandlerUtil.isGenerated(declaration)) return;
 
+		if (declaration.body == null) {
+			annotationNode.addWarning("@NonNull is meaningless on a parameter of an abstract method.");
+			return;
+		}
+
 		// Possibly, if 'declaration instanceof ConstructorDeclaration', fetch declaration.constructorCall, search it for any references to our parameter,
 		// and if they exist, create a new method in the class: 'private static <T> T lombok$nullCheck(T expr, String msg) {if (expr == null) throw NPE; return expr;}' and
 		// wrap all references to it in the super/this to a call to this method.

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

@@ -0,0 +1,10 @@
+abstract class NonNullOnParameterAbstract {
+	public void test(@lombok.NonNull String arg) {
+		if (arg == null) {
+			throw new java.lang.NullPointerException("arg");
+		}
+		System.out.println("Hey");
+	}
+
+	public abstract void test2(@lombok.NonNull String arg);
+}

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

@@ -0,0 +1,13 @@
+abstract class NonNullOnParameterAbstract {
+  NonNullOnParameterAbstract() {
+    super();
+  }
+  public void test(@lombok.NonNull String arg) {
+    if ((arg == null))
+        {
+          throw new java.lang.NullPointerException("arg");
+        }
+    System.out.println("Hey");
+  }
+  public abstract void test2(@lombok.NonNull String arg);
+}

test/transform/resource/before/NonNullOnParameterAbstract.java

@@ -0,0 +1,7 @@
+abstract class NonNullOnParameterAbstract {
+	public void test(@lombok.NonNull String arg) {
+		System.out.println("Hey");
+	}
+
+	public abstract void test2(@lombok.NonNull String arg);
+}

test/transform/resource/messages-delombok/NonNullOnParameterAbstract.java.messages

@@ -0,0 +1 @@
+6:36 @NonNull is meaningless on a parameter of an abstract method.

test/transform/resource/messages-ecj/NonNullOnParameterAbstract.java.messages

@@ -0,0 +1 @@
+6:154 @NonNull is meaningless on a parameter of an abstract method.

test/transform/resource/messages-idempotent/NonNullOnParameterAbstract.java.messages

@@ -0,0 +1 @@
+9:36 @NonNull is meaningless on a parameter of an abstract method.