Scripted REST connector to custom endpoint not returning data

1- Trying to connect to REST API http://agco-iam.herokuapp.com:80/dealerUsers.
Fine log shows data is returned (org.apache.http.impl.conn.Wire) but search results is always null.

2- With "pagedResultsCookie: null and remainingPagedResults: null" the request always fail with:

{ "message": "Could not find matching constructor for: org.identityconnectors.framework.common.objects.SearchResult(null, null)", "reason": "Internal Server Error", "code": 500 }

3- default queryFilter ("true") prevents any data from being returned (queryFilter commented out in uploaded file).