public void defer(T session, String identifier) {
        sessions.put(identifier, session);
    }
Defers the Guacamole side of authentication for the user having the
given authentication session such that it may be later resumed through a
call to resume(). If authentication is never resumed, the session will
automatically be cleaned up after it ceases to be valid.

This method accepts an externally generated ID, which should be a UUID
or similar unique identifier.

@param session
    The {@link AuthenticationSession} representing the in-progress
    authentication attempt.

@param identifier
    A unique and unpredictable string that may be used to represent the
    given session when calling resume().
guacamole-ext/src/main/java/org/apache/guacamole/net/auth/AuthenticationSessionManager.java