MessageReceiver is used to receive data from an external system.
Typically an implementation of this interface will also implement the listener
interface for the external system.
MessageTypeNotSupportedException is thrown when a message payload
is set on a Message implementation of MessageAdapter which is not of supported
type for that message or adapter.
The OutputHandler is a strategy class that is set on the StreamMessageAdapter to
defer the writing of the message payload until there is a stream available to
write it to.