Me Eric and Michael (who was guided by Mark) came to the conclusion that the Child LB of the cluster impl should be a Graceful Switch Balancer. Cluster_Impl was merged before I added Graceful Switch. It is not a strict correctness issue unlike Java at this moment, I believe the Cluster_Impl balancer functions correctly on a Type Switch with the manual type check it currently has.

Eric also mentioned writing a cross language interop test for this case.