The address specifies the physical location under which an Actor can be
reached. Examples are local addresses, identified by the ActorSystem’s
name, and remote addresses, identified by protocol, host and port.
This class is final to allow use as a case class (copy method etc.); if
for example a remote transport would want to associate additional
information with an address, then this must be done externally.
(Since version 2.8.0) use productIterator instead