move code to src/test

* so that it compiles and tests pass
* fix some additional snip references in getting started

akka-docs/src/test/java/jdocs/actor/SampleActor.java

@@ -0,0 +1,35 @@
+/**
+ * Copyright (C) 2009-2017 Lightbend Inc. <http://www.lightbend.com>
+ */
+
+package jdocs.actor;
+
+//#sample-actor
+import akka.actor.AbstractActor;
+
+public class SampleActor extends AbstractActor {
+
+  private Receive guarded = receiveBuilder()
+    .match(String.class, s -> s.contains("guard"), s -> {
+      getSender().tell("contains(guard): " + s, getSelf());
+      getContext().unbecome();
+    })
+    .build();
+
+  @Override
+  public Receive createReceive() {
+    return receiveBuilder()
+      .match(Double.class, d -> {
+        getSender().tell(d.isNaN() ? 0 : d, getSelf());
+      })
+      .match(Integer.class, i -> {
+        getSender().tell(i * 10, getSelf());
+      })
+      .match(String.class, s -> s.startsWith("guard"), s -> {
+        getSender().tell("startsWith(guard): " + s.toUpperCase(), getSelf());
+        getContext().become(guarded, false);
+      })
+      .build();
+  }
+}
+//#sample-actor