When testing setting traceCtx on commands from integration tests I ran into an issue with traceCtx being set on the command sent to mongos, mongos sends the command to mongod but we try to attach traceCtx again via the egress hook.

There doesn't seem to be a clean way of checking if traceCtx exists, deleting it, setting a new one via the egress hooks so I'm opting to do this in the RemoteCommandRequest constructor as an alternative.