Given that a series TODO mention This is a temporary hack until we have ported the MetricQueryService to the new RpcEndpoint, I'd like to give it a try to implement the RpcEndpoint version of MetricQueryService.
Basically, port onRecieve to
1. addMetric(metricName, metric, group)
And then adjust tests and replace metricServiceQueryPath with a corresponding RpcGateway.
I'd like to learn that if the statement if true — when we call a Runnable/Callable with runAsync/callAsync, then the Runnable/Callable is running in the main thread of the underlying RPC service, specifically, in the actor thread?