`REPLICA_SET_NAME` was declared as a `BasicAttributeSensorAndConfigKey` so should you use `getAttribute` instead of `getConfig`? Or just declare it as a config key if it's never set as an attribute.

The `AttributeSensorAndConfigKey` stuff is useful for if: the config could be null with the attribute then being derived somehow; or if the config has a different value (e.g. a PortRange, where as the attribute is an integer port).