+sam #13890 Add Akka Main Activator template for Java 8

akka-samples/akka-sample-main-java-lambda/src/main/java/sample/hello/HelloWorld.java

@@ -0,0 +1,26 @@
+package sample.hello;
+
+import akka.actor.AbstractActor;
+import akka.actor.Props;
+import akka.actor.ActorRef;
+import akka.japi.pf.ReceiveBuilder;
+import static sample.hello.Greeter.Msg;
+
+public class HelloWorld extends AbstractActor {
+
+  public HelloWorld() {
+    receive(ReceiveBuilder.
+      matchEquals(Msg.DONE, m -> {
+        // when the greeter is done, stop this actor and with it the application
+        context().stop(self());
+      }).build());
+  }
+
+  @Override
+  public void preStart() {
+    // create the greeter actor
+    final ActorRef greeter = getContext().actorOf(Props.create(Greeter.class), "greeter");
+    // tell it to perform the greeting
+    greeter.tell(Greeter.Msg.GREET, self());
+  }
+}