Setting persist when creating virtual server in icontrolREST

I am setting up a virtual server in icontrolREST:

 

$ curl -k -u admin:XXXX -X POST "https://pe-f5-01.pe.servicemesh.com/mgmt/tm/ltm/virtual" -d @newVIP.json -H "Content-Type:application/json"

 

Using this JSON (and whatever variants I can think of).

 

{"name":"api_test", "destination":"192.168.62.99:http", "ipProtocol":"tcp", "mask":"255.255.255.255", "pool":"api_test", "profiles":{"tcp-wan-optimized":{"context":"all"}, "http":{"context":"all"}}, "persist":{"cookie":{"default":"yes"}}}

 

In the case of this particular variant, I get this error:

 

Encountered unsupported operation add at /ltm/virtual/api_test/persist.

 

I am evidently not finding the correct syntax. Thanks for your help.