Retrieve RESTAPI JSON selected attributes in digital assistant

Summary:

Hi Experts,

We are configuring a custom skill in ODA (Oracle digital assistant) in the builder flow we have configured a REST-API call which gives output in JSON format based on previous message variable stored.

But currently we are failed to get fixed/selected attributes as an output, means for example if we want just date or assignee name for a helpdesk/case we are not able to fetch from that JSON. currently the output is full JSON payload.
Please help how to get selected output from JSON means how to get selected attribute output in Apache freemaker language.