hi I am new to llamaindex. Is there any example of directly import a KG-like json file into GPTKnowledgeGraphIndex? i.e. manually construct GPTKnowledgeGraphIndex.

I have searched related infos: the only related example I found is GPTKnowledgeGraphIndex.from_documents(), but I wonder is it necessary to construct it only by specifying index_struct, in that case there will be no docstore, will it impact the result of index.query()?