@staticmethod
def interfaces_roles_change_and_tree_was_active_and_transitions_to_unsure_and_best_upstream_neighbor_is_null(
    interface: 'TreeInterfaceUpstream'):
    """
        Interfaces roles change (NonRoot->Root) AND
        Tree transitions from Active to Unsure state AND
        BestUpstreamNeighbor is null
        """
    interface.logger.debug(
        'interfaces_roles_change_and_tree_was_active_and_transitions_to_unsure_and_best_upstream_neighbor_is_null'
        )
    interface.send_i_am_no_longer_upstream()
