@NotNull
  @Override
  public DataIndexer<MethodCallData, Void, FileContent> getIndexer() {
    return inputData -> {
      Map<MethodCallData, Void> result = new HashMap<>();

      TokenList tokens = JavaParserUtil.obtainTokens(inputData.getPsiFile());
      for (int i = 0; i < tokens.getTokenCount(); i++) {
        if (tokens.hasType(i, NULL_KEYWORD)) {
          MethodCallData data = findCallData(tokens, i);
          if (data != null) {
            result.put(data, null);
          }
        }
      }
      return result;
    };
  }
@NotNull
  @Override
  public DataIndexer<MethodCallData, Void, FileContent> getIndexer()