Add an on close callback that will be invoked by pika
        when RabbitMQ closes the connection to the publisher unexpectedly.

def add_on_connection_close_callback(self):
        """
        Add an on close callback that will be invoked by pika
        when RabbitMQ closes the connection to the publisher unexpectedly.
        """
        self._logger.debug('Adding connection close callback')
        self._connection.add_on_close_callback(self.on_connection_closed)