CallbackHandler notification for failed / aborted authentication

We should re-visit notification support to the CallbackHandler being used within Remoting.

At the moment the implemented interface focuses on the items needed by Remoting but there is no information actually passed back to the CBH.

I would suggest for backwards compatibility reasons we add a new interface that can be optionally implemented by the CBH to receive notifications, possible notifications would be: -

• About to begin auth.
• Auth successfully complete.
• Auth aborted - user rejected.
• Auth aborted - other reason.
• Connection closing.

I am not going to raise the additional jira just yet but on a slightly related note once these notifications are supported we may then want to be able to send notifications back to the connection, these notifications could allow for the number of connections from a single user to be restricted so on new connections the oldest needs to be terminated, or maybe a password reset will force re connections or even identifying a compromised password and wanting to force closed that users connections.