@Override
  public @NotNull DataIndexer<String, Void, FileContent> getIndexer() {
    return new DataIndexer<>() {
      @Override
      public @NotNull Map<String, Void> map(@NotNull FileContent inputData) {
        CharSequence text = inputData.getContentAsText();
        if (Strings.indexOf(text, XmlUtil.XML_SCHEMA_URI) == -1) {
          return Collections.emptyMap();
        }

        Map<String, Void> map = new HashMap<>();
        computeTagNames(CharArrayUtil.readerFromCharSequence(text), tag -> map.put(tag, null));
        return map;
      }
    };
  }
@Override
  public @NotNull DataIndexer<String, Void, FileContent> getIndexer()