How do you build a Knowledge Graph Index using a .json file in Llama index?

Question

I have a knowledge graph (KG) that is stored in a .json file in the ./data directory. I'm creating the index using the code below:

import os
os.environ["OPENAI_API_KEY"] = "INSERT OPENAI KEY"
from llama_index import (
    SimpleDirectoryReader,
    ServiceContext,
    KnowledgeGraphIndex,
)
from llama_index.graph_stores import SimpleGraphStore
from llama_index.llms import OpenAI
from llama_index.storage.storage_context import StorageContext


documents = SimpleDirectoryReader("./data").load_data()

llm = OpenAI(temperature=0, model="text-davinci-002")
service_context = ServiceContext.from_defaults(llm=llm, chunk_size=512)

graph_store = SimpleGraphStore()
storage_context = StorageContext.from_defaults(graph_store=graph_store)

index = KnowledgeGraphIndex.from_documents(
    documents,
    max_triplets_per_chunk=2,
    storage_context=storage_context,
    service_context=service_context,
)

Is this the correct way of loading in a KG in the form of a .json file? Or is there a more intentional way of creating the index based on a .json file?