Standalone master JSON not showing cores for running applications

The JSON API of the standalone master ("/json") does not show the number of cores for a running application, which is available on the UI.

"activeapps" : [

{ "starttime" : 1488702337788, "id" : "app-20170305102537-19717", "name" : "POPAI_Aggregated", "user" : "ibiuser", "memoryperslave" : 16384, "submitdate" : "Sun Mar 05 10:25:37 IST 2017", "state" : "RUNNING", "duration" : 1141934 }

],