redundant cast: ensure cast type compared with ground type (IDEA-174369)

remove attempts to emulate that and reuse getGroundTargetType api

java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java

@@ -425,9 +425,7 @@ public class RedundantCastUtil {
                 final PsiType parameterType = PsiTypesUtil.getParameterType(parameters, i, varargs);
                 final PsiType newArgType = newResult.getSubstitutor().substitute(parameterType);
 
-                //todo replace with castType.equals(FunctionalInterfaceParameterizationUtil.getGroundType(newArgType, lambda))
-                if (Comparing.equal(oldResult.getSubstitutor().substitute(parameterType), newArgType) &&
-                    Comparing.equal(TypeConversionUtil.erasure(castType), TypeConversionUtil.erasure(newArgType))) {
+                if (Comparing.equal(castType, ((PsiFunctionalExpression)newArgs[i]).getGroundTargetType(newArgType))) {
                   addToResults(cast);
                 }
               }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/redundantCast/GroundTargetTypeDiffersFromCastType.java

@@ -0,0 +1,18 @@
+import java.util.HashMap;
+import java.util.Map;
+
+interface A8<A1, A2> {
+    A2 a(A1 a1);
+}
+
+interface B<B1, B2> {
+    B2 b(B1 b1);
+}
+
+class Bug {
+    <T1, T2> void bug(B<T1, T2> b) {
+        Map<String, A8<?, T2>> m = new HashMap<>();
+        // replace with lambda here
+        m.put("", (A8<T1, T2>) t1 -> b.b(t1));
+    }
+} 

java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/LambdaRedundantCastTest.java

@@ -80,6 +80,7 @@ public class LambdaRedundantCastTest extends LightDaemonAnalyzerTestCase {
   public void testInvalidResolveWithoutCast() { doTest();}
   public void testCastInConditionalBranch() { doTest();}
   public void testCastInsideLambdaReturnExpressionPassedToEnumConstant() { doTest(); }
+  public void testGroundTargetTypeDiffersFromCastType() { doTest(); }
   public void testRejectReturnTypeChange() throws Exception {
     doTest();
   }