key
The key of each crud_objects child object should correspond to the resources property which uniquely identifies rows in this table. This is not strictly required, but you should typically specify a key unless there is no identifying resource in a table.
In the NIM Studio, your Keys should correspond to the keys specified here.
Example JSON:
"key": "id",
"resources": {
"id": "string*",
"primaryEmail": "string*"