empty methods hierarchy: warn about deepest methods, top empty could be of use (IDEA-146409)

java/java-impl/src/com/intellij/codeInspection/emptyMethod/EmptyMethodInspection.java

@@ -83,8 +83,8 @@ public class EmptyMethodInspection extends GlobalJavaBatchInspectionTool {
 
     String message = null;
     boolean needToDeleteHierarchy = false;
+    RefMethod refSuper = findSuperWithBody(refMethod);
     if (refMethod.isOnlyCallsSuper() && !refMethod.isFinal()) {
-      RefMethod refSuper = findSuperWithBody(refMethod);
       final RefJavaUtil refUtil = RefJavaUtil.getInstance();
       if (refSuper != null && Comparing.strEqual(refMethod.getAccessModifier(), refSuper.getAccessModifier())){
         if (Comparing.strEqual(refSuper.getAccessModifier(), PsiModifier.PROTECTED) //protected modificator gives access to method in another package
@@ -112,7 +112,7 @@ public class EmptyMethodInspection extends GlobalJavaBatchInspectionTool {
 
       message = InspectionsBundle.message("inspection.empty.method.problem.descriptor1");
     }
-    else if (areAllImplementationsEmpty(refMethod)) {
+    else if (areAllImplementationsEmpty(refMethod) && refSuper == null) {
       if (refMethod.hasBody()) {
         if (refMethod.getDerivedMethods().isEmpty()) {
           if (refMethod.getSuperMethods().isEmpty()) {

java/java-tests/testData/inspection/emptyMethod/emptyMethodsHierarchy/expected.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+ <problem>
+   <file>Derived.java</file>
+   <line>15</line>
+   <description>Empty method overrides empty method</description>
+ </problem>
+</problems>

java/java-tests/testData/inspection/emptyMethod/emptyMethodsHierarchy/src/p2/Derived.java

@@ -0,0 +1,17 @@
+package p2;
+
+class A {
+  public void foo(){
+    System.out.println("");
+  }
+}
+
+class B extends A {
+  @Override
+  public void foo() {}
+}
+
+class C extends B {
+  @Override
+  public void foo() {}
+}

java/java-tests/testSrc/com/intellij/codeInspection/EmptyMethodTest.java

@@ -49,4 +49,8 @@ public class EmptyMethodTest extends InspectionTestCase {
   public void testSuperWithoutSync() throws Exception {
     doTest();
   }
+
+  public void testEmptyMethodsHierarchy() throws Exception {
+    doTest();
+  }
 }