Timeline field is not accesible through OSLC API.

I am trying to Set, Update and Read the Timeline field.

Scenario is, I am trying to fetch the data of entity using : https://server:port/ccm/resource/itemName/com.ibm.team.workitem.WorkItem/<<entity Id>>.

Here,
Issue in fetching : Response of this API call is giving "rtc_cm:timeline": null,

Issue in writing : When trying to create the entity using post request i am passing timeline value as below.
"rtc_cm:timeline": {
    "rdf:resource": "https://server:port/ccm/oslc/timelines/<<timelineid>>"
  },
This creates entity without any exception. But, When fetching the created entity it gives null in timeline field "rtc_cm:timeline": null,

Please let me know, How can i set read and update the timeline field using OSLC JSON API.