...
And the mapping is as follows (see what get's returned by the service - JSON snippet above)
We take the "result" as a root element to look in and get the property value for "id" and for "username"
...
The end result will be like this
You can also have multiple values mapped to id or label and this is done by referencing the field values via [entry.field_name] notations. For example, if we want to show title together with username as label we can do the following
And the end result will be something like this