@Override
  public @NotNull Collection<VirtualFile> getDomFileCandidates(@NotNull Class<? extends DomElement> rootElementClass,
                                                               @NotNull GlobalSearchScope scope) {
    DomFileDescription<?> description = DomApplicationComponent
      .getInstance()
      .findFileDescription(rootElementClass);
    if (description == null) return Collections.emptySet();

    String[] namespaces = description.getAllPossibleRootTagNamespaces();
    if (namespaces.length == 0) {
      namespaces = new String[]{null};
    }
    String rootTagName = description.getRootTagName();

    Set<VirtualFile> files = new HashSet<>();
    for (String namespace : namespaces) {
      files.addAll(DomFileIndex.findFiles(rootTagName, namespace, scope));
    }
    return files;
  }
@Override
  public @NotNull Collection<VirtualFile> getDomFileCandidates(@NotNull Class<? extends DomElement> rootElementClass,
                                                               @NotNull GlobalSearchScope scope)