code-style improvements

Author: zeroDivisible

app/server/src/main/java/io/zerodi/server/handler/PingHandler.java

@@ -8,6 +8,9 @@
 import io.zerodi.messaging.amqp.MessageHandler;
 import io.zerodi.ping.PingMessage;
 
+/**
+ * Handles incoming ping messages, responding with pong.
+ */
 @Component
 public class PingHandler implements MessageHandler<PingMessage, PingMessage> {
 

component/messaging/src/main/java/io/zerodi/messaging/amqp/AmqpTemplateFactory.java

@@ -25,6 +25,10 @@
 import io.zerodi.messaging.core.UniqueId;
 import io.zerodi.messaging.core.UniqueIdFactory;
 
+/**
+ * {@link org.springframework.beans.factory.FactoryBean} which will be used to obtain preconfigured instances
+ * of {@link org.springframework.amqp.core.AmqpTemplate}
+ */
 @Primary
 @Component
 public class AmqpTemplateFactory implements FactoryBean<AmqpTemplate> {

component/messaging/src/main/java/io/zerodi/messaging/amqp/MessageHandler.java

@@ -3,7 +3,7 @@
 /**
  * When dealing with AMQP, spring allows us to use an adapter (
  * {@link org.springframework.amqp.rabbit.listener.adapter.MessageListenerAdapter}, which can be instantiated with a delegate object, to
- * which the adapter will be passing incoming requests, expecting an object being sent back, which will be serialized and sent as the
+ * which the adapter will be passing incoming messages, expecting an object being sent back, which will be serialized and sent as the
  * response. Spring is the doing some "guessing game" on finding specific method in the delegate, which should be called to handle the
  * message - implementing this interface enforces the presence of that method (<code>handleMessage</code>)
  *

component/messaging/src/main/java/io/zerodi/messaging/amqp/MessageHandlerFactory.java

@@ -6,6 +6,12 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;
 
+/**
+ * Factory which can be used to obtain preconfigured instances of {@link org.springframework.amqp.rabbit.listener.adapter.MessageListenerAdapter}
+ * <p/>
+ * <p>(messages being sent are serialized to JSON, using a {@link org.springframework.amqp.support.converter.MessageConverter},
+ * this factory makes sure that the same converter will be used in our handlers.)</p>
+ */
 @Component
 public class MessageHandlerFactory {
 

component/messaging/src/main/java/io/zerodi/messaging/amqp/SimpleMessageListenerContainerFactory.java

@@ -10,6 +10,9 @@
 import com.google.common.base.Preconditions;
 import io.zerodi.messaging.configuration.MessagingConfiguration;
 
+/**
+ * Factory which can be used to obtain preconfigured instances of {@link org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer}
+ */
 @Component
 public class SimpleMessageListenerContainerFactory {
 
@@ -31,7 +34,8 @@ public SimpleMessageListenerContainer createMessageListenerContainer(MessageList
     }
 
     private void validateInput(final Object messageListener, final Queue[] queuesToListenOn) {
-        Preconditions.checkNotNull(queuesToListenOn, "queuesToListenOn cannot be null!");
         Preconditions.checkNotNull(messageListener, "messageListener cannot be null!");
+        Preconditions.checkNotNull(queuesToListenOn, "queuesToListenOn cannot be null!");
+        Preconditions.checkArgument(queuesToListenOn.length > 0, "queuesToListenOn.length > 0 is not fulfilled!");
     }
 }

component/messaging/src/main/java/io/zerodi/messaging/async/response/ResponseContainer.java

@@ -32,8 +32,7 @@ public class ResponseContainer {
     /**
      * Notifies future (identified by id <code>uniqueId</code>, which is awaiting a response, with incoming response
      */
-    @SuppressWarnings("unchecked")
-    <T> void notifyWithResponse(@Nonnull UniqueId uniqueId, @Nonnull T response) {
+    @SuppressWarnings("unchecked") <T> void notifyWithResponse(@Nonnull UniqueId uniqueId, @Nonnull T response) {
         SettableFuture<?> future = pendingResponses.remove(uniqueId);
 
         if (future == null) {
@@ -43,7 +42,7 @@ <T> void notifyWithResponse(@Nonnull UniqueId uniqueId, @Nonnull T response) {
 
         logger.debug("notifying [ {} ] with [ {} ]", uniqueId, response);
 
-        // TODO I couldn't come with a better way of doing this, unchecked cast was the only thing which came to mind.
+        // TODO I couldn't come with a better way of doing this given the time constraints.
         ((SettableFuture<Object>) future).set(response);
     }
 

component/messaging/src/main/java/io/zerodi/messaging/async/response/ResponseListener.java

@@ -8,6 +8,10 @@
 
 import io.zerodi.messaging.core.UniqueId;
 
+/**
+ * Listener, which, when given an {@link io.zerodi.messaging.core.UniqueId}, will create a {@link java.util.concurrent.Future} which can
+ * be passed to interested parties, which will be notified when a response comes in for given id.
+ */
 public interface ResponseListener extends MessageListener {
 
     <T> Future<T> awaitResponse(@Nonnull UniqueId uniqueId);

component/messaging/src/main/java/io/zerodi/messaging/core/UniqueId.java

@@ -1,5 +1,8 @@
 package io.zerodi.messaging.core;
 
+/**
+ * Simple "unique-ish" id.
+ */
 public interface UniqueId {
 
     public String asString();

component/messaging/src/main/java/io/zerodi/messaging/service/AddressingPostProcessor.java

@@ -11,6 +11,16 @@
 import com.google.common.base.Preconditions;
 import io.zerodi.messaging.core.UniqueId;
 
+/**
+ * <p>
+ * {@link org.springframework.amqp.core.MessagePostProcessor} which is addressing outgoing messages with the details of a queue, to which
+ * responses need to be sent back
+ * </p>
+ * <p/>
+ * <p>
+ * It also sets message id & correlation id.
+ * </p>
+ */
 class AddressingPostProcessor implements MessagePostProcessor {
 
     private final Address  responseAddress;

component/messaging/src/main/java/io/zerodi/messaging/service/AmqpMessagingService.java

@@ -15,7 +15,8 @@
 import io.zerodi.messaging.core.UniqueId;
 import io.zerodi.messaging.core.UniqueIdFactory;
 
-@Service class AmqpMessagingService implements MessagingService {
+@Service
+class AmqpMessagingService implements MessagingService {
     private static final Logger logger = LoggerFactory.getLogger(AmqpMessagingService.class);
 
     @Autowired