[{"_id":"244","pubName":"p1","serviceIdRef":"36e9c779-7865-4b74-a30b-e4d6a0cc5295","serviceName":"my-service","subName":"c1","pubState":"INVITED"},{"_id":"242","pubName":"p1","serviceIdRef":"36e9c779-7865-4b74-a30b-e4d6a0cc5295","serviceName":"my-service","subName":"c1","pubState":"INVITED"},{"_id":"245","pubName":"p1","serviceIdRef":"36e9c779-7865-4b74-a30b-e4d6a0cc5295","serviceName":"my-service","subName":"c1","pubState":"ACTIVE"}]

db.collection.aggregate([{$match:{subName:{$in:["c1","c2"]},pubState:{$in:["INVITED","ACTIVE"]}}},{$sort:{_id:-1}},{$group:{_id:{serviceIdRef:"$serviceIdRef",pubState:"$pubState"},serviceName:{$first:"$serviceName"},sample:{$push:"$$ROOT"},count:{$sum:1}}},{$group:{_id:"$_id.serviceIdRef",serviceName:{$first:"$serviceName"},state:{$push:{pubState:"$_id.pubState",count:"$count",sample:{$slice:["$sample",2]}}}}}])