Issue in passing CHEF:ChefHost parameter for Chef Workflow in vRealize Orchestrator API

I have an environment with vRealize Orchestrator with CHEF plugin installed. I want to call the API for initiating a CHEF workflow in vRealize Orchestrator.

Say I want to call the CHEF workflow Add New Role. The input parameters for this workflow are

<input-parameters>     <parameter description="Chef Server" type="CHEF:ChefHost" name="host"/>     <parameter description="Name of new role" type="string" name="role"/>     <parameter description="(Optional) Description of new role" type="string" name="description"/></input-parameters>

The format for sending parameters of the form type="string" is

In JSON

{     "value":{"string":{"value": "role name"}},     "type": "string",     "name": "role"
}

In XML

<execution-context xmlns="http://www.vmware.com/vco">  <parameters>       <parameter name="role" type="string">            <string>Role Name</string>       </parameter>  </parameters></execution-context>

The problem I'm facing is with the parameter type="CHEF:ChefHost". I can't get the correct syntax for sending type="CHEF:ChefHost". When testing with Postman, I'm always getting a 400 error with description The request sent by the client was syntactically incorrect.

Is there any document which shows how to create a CHEF:ChefHost type?

PS: I asked this question in http://stackoverflow.com/questions/37405901/issue-in-passing-chefchefhost-parameter-for-chef-workflow-in-vrealize-orches…

Since I didn't get an answer from SO, I'm asking it here.