Get on specific object does not work from ODL when this object has composite key, and one of key is union where first order is instance-identifier

For ietf-alarms.yang, when there is retrieval (GET) operation performed, then no output displays on postman, but same works fine, if GET ALL is performed via ODL for alarm-list object.

This alarm-list object has composite key, [alarm-type-id][alarm-type-qualifier][resource]

Here resource is union of instance-identifier, yang xpath,  object identifier, and string

From Server side this attribute resource has been made as "instance-identifier"/ 

http://HOST:8181/restconf/operational/network-topology:network-topology/topology/topology-netconf/node/Node2/yang-ext:mount/ietf-alarms:alarms/ietf-alarms:alarm-list/ietf-alarms:alarm/:resource/:alarm-type-id/:alarm-type-qualifier

resource %2Foc-platform%3Acomponents%2Foc-platform%3Acomponent%5Boc-platform%3Aname%3D'slot-1-6'%5D

alarm-type-id infinera-ietf-alarms-extensions%3Aseverity-default-level-changed

alarm-type-qualifier GX%2525na%2525na

under Params/Key these have been given.

From NE porper response comes, and in ODL logs response object is visible, but resource is not parsed properly.