We have two nearly identical ReadWriteConcernDefaults server status sections, in read_write_concern_defaults_server_status.cpp and s_read_write_concern_defaults_server_status.cpp , for mongod/mongos respectively.

We should clean this up, especially because given that mongod can act as a router now, mongos should not have separately linked behavior. In this case, the behavior is essentially identical, so we should consolidate the classes.