l)    /**    * This message is understood by the connection actors to send data to their    * designated destination. The connection actor will respond with    * [[CommandFailed]] if the send could not be enqueued to the O/S kernel    * because the send buffer was full. If the given `ack` is not of type [[NoAck]]    * the connection actor will reply with the given object as soon as the datagram    * has been successfully enqueued to the O/S kernel.    */   