private @Nullable ProblemDescriptor getRedundantCaseChangeProblem(PsiMethodCallExpression call) {
      PsiMethodCallExpression qualifierCall = MethodCallUtils.getQualifierMethodCall(call);
      if (CASE_CHANGE.test(qualifierCall)) {
        return getProblem(qualifierCall, "inspection.redundant.string.call.message");
      }
      return null;
    }
private @Nullable ProblemDescriptor getRedundantCaseChangeProblem(PsiMethodCallExpression call)