mod_http_oauth2: Record hash of client_id to allow future verification RFC 6819 section 5.2.2.2 states that refresh tokens MUST be bound to the client. In order to do that, we must record something that can definitely tie the client to the grant. Since the full client_id is so large (why we have this client_subset function), a hash is stored instead.

This module discards typing notifications sent to a bare host JID,
preventing error replies to be sent. These errors are harmless but can
be annoying sometimes if your client shows them prominently.