This member is added by an implicit conversion from HasSequenceNumber to
any2stringadd[HasSequenceNumber] performed by method any2stringadd in scala.Predef.
This member is added by an implicit conversion from HasSequenceNumber to
StringFormat[HasSequenceNumber] performed by method StringFormat in scala.Predef.
Messages that are to be buffered in akka.remote.AckedSendBuffer or akka.remote.AckedReceiveBuffer has to implement this interface to provide the sequence needed by the buffers.