def ref_doc_info(self) -> Dict[str, RefDocInfo]:
        """Retrieve a dict mapping of ingested documents and their nodes+metadata."""
        raise NotImplementedError(
            "Ref doc info not implemented for PropertyGraphIndex. "
            "All inserts are already upserts."
        )
Retrieve a dict mapping of ingested documents and their nodes+metadata.
llama-index-core/llama_index/core/indices/property_graph/base.py