static @Nullable <T extends DomElement> DomFileElementImpl<T> getCachedFileElement(@NotNull XmlFile file) {
    //noinspection unchecked
    return (DomFileElementImpl<T>)SoftReference.dereference(file.getUserData(CACHED_FILE_ELEMENT));
  }
static @Nullable <T extends DomElement> DomFileElementImpl<T> getCachedFileElement(@NotNull XmlFile file)