[DISCUSS] KIP-190: Handle client-ids consistently between clients and brokers

[Mickael Maison]

Hi all,

I have created a KIP to cleanup the way client-ids are handled by
brokers and clients.

Currently the Java clients have some restrictions on the client-ids
that are not enforced by the brokers. Using 3rd party clients,
client-ids containing any characters can be used causing some strange
behaviours in the way brokers handle metrics and quotas.

Feedback is appreciated.

Thanks