Error occurs when we use brg_only script to create vBRG concurrently in the vf module creation step:
"statusMessage": "Received error from SDN-C: vf-module not found in AnAI with vf-module-id = 7d5e029c-94ae-485c-ba7e-794a70c2955d and generic-vnf-id = 266c7414-8fdc-48ea-9f2a-d409fc5ff14c"

After discussion with Brian and Yang Xu, we suspect wait_for_AAI() is needed during the creation of vf module in vBRG instantiation.