private static void processCallsWithNullArguments(@NotNull PsiMethod method,
                                                    int argumentIdx,
                                                    @NotNull Processor<? super PsiExpression> nullArgumentProcessor,
                                                    Collection<? extends VirtualFile> candidateFiles) {
    if (candidateFiles.isEmpty()) return;

    GlobalSearchScope scope = GlobalSearchScope.filesScope(method.getProject(), candidateFiles);
    MethodReferencesSearch.search(method, scope, true).forEach(ref -> {
      PsiExpression argument = getCallArgument(ref, argumentIdx);
      if (argument instanceof PsiLiteralExpression && argument.textMatches(PsiKeyword.NULL)) {
        return nullArgumentProcessor.process(argument);
      }
      return true;
    });
  }
private static void processCallsWithNullArguments(@NotNull PsiMethod method,
                                                    int argumentIdx,
                                                    @NotNull Processor<? super PsiExpression> nullArgumentProcessor,
                                                    Collection<? extends VirtualFile> candidateFiles)