SDN-C output for datanodes seems to include a 'prefix' for the top level (node) and possibly other nodes (when entering separate modules?)

The intention is dat client can easily switch between passthrough and non-passthrough queries without affect on the output format for Yang modelled nodes. 

This user story is to propose a solution to ensure this alignment

As discussed on 27/04/2022:

The proposal is to add module name prefix to cps-core output because passthrough output cannot be modified.

Sample passthrough query:

curl -X 'GET' --user cpsuser:cpsr0cks! "http://localhost:8883/ncmp/v1/ch/22/data/ds/ncmp-datastore:passthrough-running?resourceIdentifier=ran-network:ran-network/NearRTRIC=22/GNBDUFunction
=660/NRCellDU=15361/attributes" -H 'accept: application/json' -i
'ran-network' is prefixed in the output of above request

{
  "ran-network:attributes":{
     "sAP":[
       { "host":"localhost", "port":8080 }
     ],
     "nRSectorCarrierRef":[
       "OU=Sales"
     ],
     "cellLocalId":15361,
     "administrativeState":"UNLOCKED",
     "nRPCI":12,
     "nRTAC":310
  }
}

 Implementation details

Get prefix from schemaset using schemaset cache (YangTextSchemaSourceSetCache)

Use of ODL to convert Yang to a java object, see also org.onap.cps.yang.YangTextSchemaSourceSetBuilder#generateSchemaContext

(possibly start caching these objects in a new cache too - using the same key)

Open Issues

1. If the child is in a different module should it have a prefix
2. If the output starts with non-root element should it have a prefix
3. Discuss backward incompatibility with stakeholders
   1. WiPro (E2E Slicing)
   2. Ericsson
   3. Bell (Bruno has confirmed that they are not impacted ?)

A/C

1. Demo the correct prefix is added just to the root element
2. agree with stakeholders what to do with the backward incompatibility

Out-of-scope

1. Implementation for open issue #1 (handled in separate user story as E2E slining probably won't depend on this)