public void reactivateSession(String identifier) {

        // Remove from the set of pending sessions to reactivate
        if (identifier != null)
            pendingSessions.remove(identifier);

    }
Reactivate (remove from pending) the session associated with the given
session identifier, if any. After calling this method, any session with
the given identifier will be ready to be resumed again.

@param identifier
    The identifier of the session to reactivate, if one exists.
guacamole-ext/src/main/java/org/apache/guacamole/net/auth/AuthenticationSessionManager.java