[{"username":"vara","fullname":"john","rolesAgg":[{"_id":ObjectId("5d5cf8ceb3773255b54d18c3"),"name":"Super Admin"},{"_id":ObjectId("5d5cf8ceb3773255b54d18c4"),"name":"Admin"},{"_id":ObjectId("5d5cf8ceb3773255b54d18c5"),"name":"Customer Service"}]}]

db.collection.aggregate([{"$unwind":"$rolesAgg"},{"$sort":{"rolesAgg.name":-1}},{$group:{_id:"$_id",username:{"$first":"$username"},"fullname":{"$first":"$fullname"},rolesAgg:{$push:"$rolesAgg"}}}])