Moved spring-akka to a separate project (#560)

spring-akka/src/main/java/org/baeldung/akka/SpringExtension.java

@@ -0,0 +1,33 @@
+package org.baeldung.akka;
+
+import akka.actor.AbstractExtensionId;
+import akka.actor.ExtendedActorSystem;
+import akka.actor.Extension;
+import akka.actor.Props;
+import org.springframework.context.ApplicationContext;
+
+public class SpringExtension extends AbstractExtensionId<SpringExtension.SpringExt> {
+
+    public static final SpringExtension SPRING_EXTENSION_PROVIDER = new SpringExtension();
+
+    @Override
+    public SpringExt createExtension(ExtendedActorSystem system) {
+        return new SpringExt();
+    }
+
+    public static class SpringExt implements Extension {
+
+        private volatile ApplicationContext applicationContext;
+
+        public void initialize(ApplicationContext applicationContext) {
+            this.applicationContext = applicationContext;
+        }
+
+        public Props props(String actorBeanName) {
+            return Props.create(SpringActorProducer.class, applicationContext, actorBeanName);
+        }
+
+    }
+
+
+}