Group Provision param: entityNameExp doen't seem to work.

[mrutid]

Given the following group:

{
    "attributes" : [ 
        {
            "name" : "myAtt",
            "type" : "text"
        }
    ],
    "resource" : "/iot/json",
    "apikey" : "key",
    "type" : "MySensorGroup",
    **"entityNameExp" : "'expression'+id",**
    "service" : "myserv",
    "subservice" : "MySServ",
    "expressionLanguage" : "jexl",
}

We get the following NGSI update:

http://eob67h2l2jqr93n.m.pipedream.net/v2/entities/MySensorGroup2:007/attrs?type=MySensorGroup2

instead of

http://eob67h2l2jqr93n.m.pipedream.net/v2/entities/expression007/attrs?type=MySensorGroup2