provide extends fix for overriding return types (IDEA-161739)

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightMethodUtil.java

@@ -213,6 +213,10 @@ public class HighlightMethodUtil {
       description).create();
     QuickFixAction.registerQuickFixAction(errorResult, QUICK_FIX_FACTORY.createMethodReturnFix(method, substitutedSuperReturnType, false));
     QuickFixAction.registerQuickFixAction(errorResult, QUICK_FIX_FACTORY.createSuperMethodReturnFix(superMethod, returnType));
+    final PsiClass returnClass = PsiUtil.resolveClassInClassTypeOnly(returnType);
+    if (returnClass != null && substitutedSuperReturnType instanceof PsiClassType) {
+      QuickFixAction.registerQuickFixAction(errorResult, QUICK_FIX_FACTORY.createChangeParameterClassFix(returnClass, (PsiClassType)substitutedSuperReturnType));
+    }
 
     return errorResult;
   }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/changeParameterClass/afterReturnTypeChanged.java

@@ -0,0 +1,19 @@
+// "Make 'Bar' implement 'java.lang.Runnable'" "true"
+
+abstract class Foo {
+    abstract Runnable foo();
+}
+
+class FooBar extends Foo {
+    @Override
+    Bar foo() {
+        return null;
+    }
+
+    static class Bar implements Runnable {
+        public void run() {
+            <caret>
+        }
+    }
+}
+

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/changeParameterClass/beforeReturnTypeChanged.java

@@ -0,0 +1,15 @@
+// "Make 'Bar' implement 'java.lang.Runnable'" "true"
+
+abstract class Foo {
+    abstract Runnable foo();
+}
+
+class FooBar extends Foo {
+    @Override
+    B<caret>ar foo() {
+        return null;
+    }
+
+    static class Bar {}
+}
+