Is there a XLAT IF(..) like expansion?

[g4-lisz at tonarchiv.ch]

Hello again 

I'm trying to accomplish the following (pseudo code):

In rlm_rest module config:

authenticate {
 body = "json"
 data = '{ 
 "token" : "xxxxxxx", 
 "states": [ "x", "y" ], 
 "resourceIds: PSEUDO_CODE>> IF(%{control:Cust-Resource-Uuid}, [ "%{control:Cust-Resource-Uuid}" ], null) <<PSEUDO_CODE , 
 }'
}

I.e. when the custom attribute is set, the JSON's "resourcesIds" property should be an array containing the attribute's string content, otherwise "null".

Your help is much appreciated!

Cheers,
Till