@NotNull
  private static String readAttributeFromFile(@NotNull VirtualFile file) {
    byte[] data;
    try {
      data = CALL_SIGNATURES_ATTRIBUTE.readAttributeBytes(file);
    }
    catch (Exception e) {
      data = null;
    }

    String content;
    if (data != null && data.length > 0) {
      content = new String(data, StandardCharsets.UTF_8);
    }
    else {
      content = null;
    }
    return content != null ? content : "";
  }
@NotNull
  private static String readAttributeFromFile(@NotNull VirtualFile file)