Incomplete json response from PostMan as client

I am making a call to below api from postman. Strangely , in the json response the attribute "ui_policy" is empty. However, when I do the same thing from SN's REST API Explorer, I do get the ui_policy for the catalog item. Does it mean that any external app cannot fire a rest api to get this attribute?

Here is the api:
GET https://{xxx}/api/sn_sc/servicecatalog/items/{sys_id}