anchor.diff:  [source,json,linenums]
   ----
   {
  -   "userId":"kermit"
  +   "user":"kermit"
   }
   ----
   
  
positive.code: |Parameter|Required|Value|Description
  |processDefinitionId|Yes|String|The id of the process definition.
  |family|Yes|String|Either +users+ or +groups+, depending on the type of identity link.
  |identityId|Yes|String|Either the userId or groupId of the identity to get as candidate starter.
  
  |===============
  
  
negative.code: ----
  
  
  Note that the +group+ will always be null, as it's only possible to involve users with a process-instance.
  
  
  ==== Remove an involved user to from process instance
  