Decruft the broker by removing Event interface (#1940)

broker/broker.go

@@ -16,21 +16,15 @@ type Broker interface {
 // Handler is used to process messages via a subscription of a topic.
 // The handler is passed a publication interface which contains the
 // message and optional Ack method to acknowledge receipt of the message.
-type Handler func(Event) error
+type Handler func(*Message) error
+
+type ErrorHandler func(*Message, error)
 
 type Message struct {
 	Header map[string]string
 	Body   []byte
 }
 
-// Event is given to a subscription handler for processing
-type Event interface {
-	Topic() string
-	Message() *Message
-	Ack() error
-	Error() error
-}
-
 // Subscriber is a convenience return type for the Subscribe method
 type Subscriber interface {
 	Options() SubscribeOptions