How to override Smart Class Parameter - override value?

"created_at": "2017-04-18 07:54:50 UTC",
"updated_at": "2017-05-04 03:21:15 UTC",
"id": 9,
"match": "",
"value": {
"proxyserver": {
"server_name": [
"omit": false,
"use_puppet_default": false
I would like to add more to the proxyserver item. But no matter how I call
the API:
it returns 200 code but not updated.

I have even tried it with change "omit" to true like:
curl -k -u user:password -H "Accept: version=2,application/json" -H
"Content-Type: application/json" -X PUT -d
So please help on how to call this API? a curl example would be appreciated.