We have tcp listener, udp listener, api listener in the same Listener message ,
and I am adding another internal listener.

These listeners have their own feature set. e.g. connection_balance_config should not be used by udp listener, filter_chains should only be used by tcp listener (and quic ?), not all sock options are for udp, vice versa.

We don't have adequate validation for the above implicit rules for now.

It's probably good to warn the user upon receiving listener config, starting from "some fields are contradicting or ignored" and eventually reject inconsistent config.

WDYT?