Try below queries
1) path=/content/dam
1_property=jcr:content/related/derived/sling:members/@sling:resources
1_property.value=/content/dam%
1_property.operation=like
p.limit=-1
2) type=dam:Asset
p.hits=selective
1_property=jcr:content/related/derived/sling:members/@sling:resources
1_property.value=/content/dam%
1_property.operation=like
p.limit=-1

In both the results I am getting the results.
To return the json below is the link for above query
http://localhost:4502/bin/querybuilder.json?1_property=jcr%3acontent%2frelated%2fderived%2fsling%3amembers%2f%40sling%3aresources&1_property.operation=like&1_property.value=%2fcontent%2fdam%25&p.hits=selective&p.limit=-1&type=dam%3aAsset

In order to return results in desired format, you can write a servlet which will process the output of query builder and add the response to required format.