@Override
      public @NotNull Map<DomIndexKey, Void> map(@NotNull FileContent inputData) {
        XmlFileHeader header = NanoXmlUtil.parseHeader(CharArrayUtil.readerFromCharSequence(inputData.getContentAsText()));
        String rootTagName = header.getRootTagLocalName();
        if (rootTagName == null) {
          return Collections.emptyMap();
        }

        String[] namespaces = new String[]{header.getPublicId(), header.getSystemId(), header.getRootTagNamespace(), NULL_NAMESPACE};
        Map<DomIndexKey, Void> set = new HashMap<>(namespaces.length);
        for (String t : namespaces) {
          if (t != null) {
            set.put(new DomIndexKey(rootTagName, t), null);
          }
        }
        return set;
      }
@Override
      public @NotNull Map<DomIndexKey, Void> map(@NotNull FileContent inputData)