skip extends Object during new type param creation; test for IDEA-57449

java/java-psi-impl/src/com/intellij/psi/impl/PsiElementFactoryImpl.java

@@ -178,9 +178,10 @@ public class PsiElementFactoryImpl extends PsiJavaParserFacadeImpl implements Ps
   public PsiTypeParameter createTypeParameter(String name, PsiClassType[] superTypes) {
     StringBuilder builder = new StringBuilder();
     builder.append("public <").append(name);
-    if (superTypes.length > 0) {
+    if (superTypes.length > 1) {
       builder.append(" extends ");
       for (PsiClassType type : superTypes) {
+        if (type.equalsToText(CommonClassNames.JAVA_LANG_OBJECT)) continue;
         builder.append(type.getCanonicalText()).append(',');
       }
 

java/java-tests/testData/codeInsight/overrideImplement/afterResolveTypeParamConflict.java

@@ -0,0 +1,10 @@
+abstract class A1<X>{
+    abstract <T> void foo(T t, X x);
+}
+
+class B1<T> extends A1<T>{
+    @Override
+    <T1> void foo(T1 t1, T t) {
+        <selection>//To change body of implemented methods use File | Settings | File Templates.</selection>
+    }
+}

java/java-tests/testData/codeInsight/overrideImplement/beforeResolveTypeParamConflict.java

@@ -0,0 +1,7 @@
+abstract class A1<X>{
+    abstract <T> void foo(T t, X x);
+}
+
+class B1<T> extends A1<T>{
+  <caret>
+}

java/java-tests/testSrc/com/intellij/codeInsight/OverrideImplementTest.java

@@ -63,6 +63,7 @@ public class OverrideImplementTest extends LightCodeInsightTestCase {
   public void testSimplifyObjectWildcard() { doTest(false); }
   public void testErasureWildcard() { doTest(false); }
   public void testMultipleInterfaceInheritance() { doTest(false); }
+  public void testResolveTypeParamConflict() { doTest(false); }
 
   public void testImplementExtensionMethods() { doTest8(false, true); }
   public void testDoNotImplementExtensionMethods() { doTest8(false, true); }