anchor.diff:      .receiverChannel("udp://239.1.1.1:12001"));
   ----
   
  +=== Heartbeats
  +
  +AeronPublisher sends heartbeats to the instance of AeronSubscriber it is connected to
  +every `Context.heartbeatIntervalMillis' milliseconds. When the subscriber doesn't receive
  +any heartbeat from the publisher during the heartbeat interval * 1.5 it considers the session
  +with the publisher disconnected.
  +
  +When the publisher can't publish a heartbeat to the subscriber `Context.maxHeartbeatPublicationFailures`
  +times in a row then it shuts itself down.
  +
  +=== Auto-cancel functionality
  +
  +Both AeronSubscriber and AeronPublisher support auto-cancel functionality.
  +
  +When AeronSubscriber is created with `Context.autoCancel` set to true
  +it terminates its upstream subscription when the last publisher disconnects.
  +
  +When AeronPublisher is created with `Context.autoCancel` set to true
  +it shuts itself down when its subscriber is terminated as it expects the
  +corresponding subscriber instance it's connecting to to operate in auto-cancel
  +mode as well.
  +
   === Handling errors
   
   Error handler can be specified via `Context.errorConsumer` and is set by default to an error consumer logging exceptions.
  
positive.code:     .senderChannel("udp://serverbox:12000"));
  ----
  
  ==== Multicast sending mode
  
  To configure AeronSubscriber in multicast mode set field 'Context.receiverChannel' to a multicast Aeron channel.
  
negative.code:     .senderChannel("udp://serverbox:12000")
      .receiverChannel("udp://239.1.1.1:12001"));
  ----
  
  ==== Multiple sessions support for multicast
  
  As in case of unicast AeronSubscriber supports multiple sessions in multicast mode as well.
  In multicast mode all sessions between an instance of AeronSubscriber and AeronPublishers
  are handled in a single thread.
  
  A slow AeronPublisher connected to AeronSubscriber will eventually backpressure the subscriber
  and as a result a fast consuming publisher will block.
  
  A single request for signals to upstream subscription of AeronSubscriber is made for
  `Context.multicastUpstreamRequest`. Once signals are requested from the upstream they
  are send into Aeron to all connected publishers and each publisher demand adjusted within its
  session.
  
  === AeronPublisher as client
  
  