document EventStream, see #1507

- fix some Java API issues
- also mention dead letters, see #1491

akka-actor/src/main/scala/akka/event/japi/EventBusJavaAPI.scala

@@ -3,7 +3,7 @@ package akka.event.japi
 import akka.event._
 
 /**
- * See documentation for akka.event.LookupClassification
+ * See documentation for [[akka.event.LookupClassification]]
  * E is the Event type
  * S is the Subscriber type
  * C is the Classifier type
@@ -15,7 +15,19 @@ abstract class LookupEventBus[E, S, C] extends EventBus with LookupClassificatio
 }
 
 /**
- * See documentation for akka.event.ScanningClassification
+ * See documentation for [[akka.event.SubchannelClassification]]
+ * E is the Event type
+ * S is the Subscriber type
+ * C is the Classifier type
+ */
+abstract class SubchannelEventBus[E, S, C] extends EventBus with SubchannelClassification {
+  type Event = E
+  type Subscriber = S
+  type Classifier = C
+}
+
+/**
+ * See documentation for [[akka.event.ScanningClassification]]
  * E is the Event type
  * S is the Subscriber type
  * C is the Classifier type
@@ -27,12 +39,11 @@ abstract class ScanningEventBus[E, S, C] extends EventBus with ScanningClassific
 }
 
 /**
- * See documentation for akka.event.ActorClassification
+ * See documentation for [[akka.event.ActorClassification]]
  * An EventBus where the Subscribers are ActorRefs and the Classifier is ActorRef
  * Means that ActorRefs "listen" to other ActorRefs
  * E is the Event type
  */
-
 abstract class ActorEventBus[E] extends akka.event.ActorEventBus with ActorClassification with ActorClassifier {
 
 }