Yang Data Codec Gson: null pointer exception when trying to deserialize leafref value

When trying to call Rpc with input that has extended types referencing leafref nodes from another module, parsing of Json fails with null pointer exception.

example model:
(nt is network-topology module)
leaf node

{ mandatory true; type nt:node-ref; description "Network node end point."; }

leaf-list supporting-tp

{ type nt:tp-ref; description "List of termination points that support end point TP. If forwarding adjacency announcement triggers termination point creation, this list is used to fill tp-ref attribute."; }

leaf tp-id

{ type nt:tp-id; description "Forwarding adjacency interface unique identifier. If forwarding adjacency announcement triggers termination point creation, this id is used for TP creation."; }

Bug can be reproduced by calling this rpc from topoproccessing project: http://127.0.0.1:8181/restconf/operations/multilayer-topology:forwarding-adj-announce

input:
{
"input": {
"head-end":

{ "node": "A", "supporting-tp": [ "/network-topology/topology[topology-id='TOPO']/node[node-id='1']/termination-point[network-topology:tp-id='1:3']" ], "tp-id": "A:1" }

,
"tail-end":

{ "node": "B", "supporting-tp": [ "/network-topology/topology[topology-id='TOPO']/node[node-id='2']/termination-point[network-topology:tp-id='2:3']" ], "tp-id": "B:1" }

,
"bidirectional" : {}
}
}