[groovy] do not highlight default parameters in abstract methods as forbidden (IDEA-128293)

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/annotator/GroovyAnnotator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2015 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -736,6 +736,7 @@ public class GroovyAnnotator extends GroovyElementVisitor {
 
   private static void checkOptionalParametersInAbstractMethod(AnnotationHolder holder, GrMethod method) {
     if (!method.hasModifierProperty(PsiModifier.ABSTRACT)) return;
+    if (!(method.getContainingClass() instanceof GrInterfaceDefinition)) return;
 
     for (GrParameter parameter : method.getParameters()) {
       GrExpression initializerGroovy = parameter.getInitializerGroovy();

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/highlighting/Groovy23HighlightingTest.groovy

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -82,5 +82,14 @@ def foo() {
 ''')
   }
 
+  void 'test default parameter in trait methods'() {
+    testHighlighting '''\
+trait T {
+  abstract foo(x = 3);
+  def bar(y = 6) {}
+}
+'''
+  }
+
   final InspectionProfileEntry[] customInspections = [new GroovyAssignabilityCheckInspection(), new GrUnresolvedAccessInspection()]
 }

plugins/groovy/testdata/highlighting/DefaultInitializersAreNotAllowedInAbstractMethods.groovy

@@ -3,7 +3,35 @@ interface I {
 }
 
 abstract class A {
-  abstract foo(int x<error descr="Default initializers are not allowed in abstract methods"> = 5</error>)
+  abstract foo(int x = 5)
 
   def abr(int x = 5){}
 }
+
+enum E {
+  ONE {
+    def foo(x) {}
+  };
+
+  abstract foo(x = 3)
+  def bar(y = 12) {}
+}
+
+@interface An {
+  int foo()
+  String bar(x = 2)
+}
+
+def a = new Runnable() {
+  void run() {}
+  <error descr="Anonymous class cannot have abstract method">abstract</error> foo(x = 5);
+}
+
+enum EE {
+  T {
+    def foo() {}
+    <error descr="Anonymous class cannot have abstract method">abstract</error> bar(x = 4);
+  };
+
+  def foo() {}
+}