"Operation is not supported for selector" when using "Update datasources" REST API

I am trying to automate the publishing of a .pbix file, then change the "url" value of the OData datasource, in order to have a way to automation deployment from dev->test->prod.  When I make an http post to:

https://api.powerbi.com/v1.0/myorg/groups/{valid-group-id}/datasets/{valid-dataset-id}/updatedatasources
...with the following body:
{
  "updateDetails":[
    {
      "connectionDetails":
      {
        "url": "https://new-value.api.crm.dynamics.com/api/data/v8.2"
      },
      "datasourceSelector":
      {        
        "datasourceType": "OData",
        "connectionDetails": 
        {
          "url":"https://old-value.api.crm.dynamics.com/api/data/v8.2"
        }
      }
    }
  ]
}
...the status is 400 with an "Operation is not supported for selector".  However, according to my interpretation of https://msdn.microsoft.com/en-us/library/mt814715.aspx this should be supported.  Any thoughts on why I am getting this error?