anchor.diff:  <pre class="terminal">
   $ curl http://username:password@broker-url/v2/service_instances/:instance_id -d '{
     "plan_id": "plan-guid-here"
  -}' -X PATCH -H "X-Broker-API-Version: 2.4" -H "Content-Type: application/json"
  +}' -X PATCH -H "X-Broker-API-Version: 2.5" -H "Content-Type: application/json"
   </pre>
   
   ### Response ###
  
positive.code: These fields must be optional and should be ignored by clients and servers
  that do not understand them.
  
  ### <a id='api-changes-since-v2-3'></a>Changes Since v2.3 ###
  
  The key change from v2.3 to v2.5 is support for users to change the service plan for a specified service instance.
  
  ## <a id='dependencies'></a>Dependencies ##
  
  
negative.code:   "plan_id":           "plan-guid-here",
    "organization_guid": "org-guid-here",
    "space_guid":        "space-guid-here"
  }' -X PUT -H "X-Broker-API-Version: 2.5" -H "Content-Type: application/json"
  </pre>
  
  In this case, `instance_id` refers to the service instance id generated by Cloud
  