@Override
  public Map<VirtualFile, Set<String>> getInfo(final boolean useCommonExtension) {
    if (! useCommonExtension) {
      return folders;
    }
    final Map<VirtualFile, Set<String>> result = new HashMap<>(folders.size(), 1);
    for (final Map.Entry<VirtualFile, Set<String>> entry : folders.entrySet()) {
      final Set<String> set = new HashSet<>();
      set.add(getExtensionMask());
      result.put(entry.getKey(), set);
    }
    return result;
  }
@Override
  public Map<VirtualFile, Set<String>> getInfo(final boolean useCommonExtension)