private static @Nullable BidirectionalMap<String, String> getNamespaceMap(@NotNull XmlTag tag) {
    return CachedValuesManager.getCachedValue(tag, () ->
      Result.create(computeNamespaceMap(tag), PsiModificationTracker.MODIFICATION_COUNT));
  }
private static @Nullable BidirectionalMap<String, String> getNamespaceMap(@NotNull XmlTag tag)