diff --git a/org.springframework.integration/src/main/java/org/springframework/integration/aggregator/MessageGroup.java b/org.springframework.integration/src/main/java/org/springframework/integration/aggregator/MessageGroup.java
index 28d6123a45..68bd0e2493 100644
--- a/org.springframework.integration/src/main/java/org/springframework/integration/aggregator/MessageGroup.java
+++ b/org.springframework.integration/src/main/java/org/springframework/integration/aggregator/MessageGroup.java
@@ -1,106 +1,131 @@
+/*
+ * Copyright 2002-2010 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.springframework.integration.aggregator;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
 import org.springframework.integration.core.Message;
 
-import java.util.*;
-
 /**
- * Represents an mutable group of correlated messages that is bound to a certain
- * {@link org.springframework.integration.store.MessageStore}
- * and correlation key. The group will grow during its lifetime, when messages are <code>add</code>ed to it. <strong>
- * This is not thread safe and should not be used for long running aggregations</strong>.
+ * Represents a mutable group of correlated messages that is bound to a certain
+ * {@link org.springframework.integration.store.MessageStore} and correlation
+ * key. The group will grow during its lifetime, when messages are <code>add</code>ed to it.
+ * <strong>This is not thread safe and should not be used for long running aggregations</strong>.
  * <p/>
- * According to its {@link org.springframework.integration.aggregator.CompletionStrategy} it can be <i>complete</i>
- * depending on the messages in the group.
+ * According to its
+ * {@link org.springframework.integration.aggregator.CompletionStrategy} it can
+ * be <i>complete</i> depending on the messages in the group.
  * <p/>
- * Optionally MessageGroupListeners can be added to get callbacks when (parts of) the group are processed or the whole
- * group is completed.
- *
- *
+ * Optionally MessageGroupListeners can be added to get callbacks when (parts
+ * of) the group are processed or the whole group is completed.
+ * 
  * @author Iwein Fuld
  * @author Oleg Zhurakousky
+ * @since 2.0
  */
 public class MessageGroup {
-    private final CompletionStrategy completionStrategy;
-    private final Object correlationKey;
-    private final ArrayList<Message<?>> messages = new ArrayList<Message<?>>();
-    private final List<MessageGroupListener> listeners;
+
+	private final CompletionStrategy completionStrategy;
+
+	private final Object correlationKey;
+
+	private final ArrayList<Message<?>> messages = new ArrayList<Message<?>>();
+
+	private final List<MessageGroupListener> listeners;
 
 
-    public MessageGroup(Collection<? extends Message<?>> originalMessages, CompletionStrategy completionStrategy,
-                        Object correlationKey, MessageGroupListener... listeners) {
-        this.completionStrategy = completionStrategy;
-        this.correlationKey = correlationKey;
-        this.messages.addAll(originalMessages);
-        this.listeners = Collections.unmodifiableList(Arrays.asList(listeners));
-    }
+	public MessageGroup(Collection<? extends Message<?>> originalMessages, CompletionStrategy completionStrategy,
+			Object correlationKey, MessageGroupListener... listeners) {
+		this.completionStrategy = completionStrategy;
+		this.correlationKey = correlationKey;
+		this.messages.addAll(originalMessages);
+		this.listeners = Collections.unmodifiableList(Arrays.asList(listeners));
+	}
 
-    /**
-     * This method determines whether messages have been added to this group that supersede the given message based on
-     * its sequence id. This can be helpful to avoid ending up with sequences larger than their required sequence size,
-     * or sequences that are missing certain sequence numbers.
-     */
-    public boolean hasNoMessageSuperseding(Message<?> message) { 	
-        Integer messageSequenceNumber = message.getHeaders().getSequenceNumber();
-        if (messageSequenceNumber > 0){
-        	if (messageSequenceNumber == null) {
-                return true;
-            }
-            for (Message<?> member : messages) {
-                Integer memberSequenceNumber = member.getHeaders().getSequenceNumber();
-                if (memberSequenceNumber.equals(messageSequenceNumber)) {
-                    return false;
-                }
-            }
-    	} 
-        return true;
-    }
 
-    /**
-     * Add a message to the internal list. This is needed to avoid hitting the underlying store or copying the internal
-     * list. Use with care.
-     */
-    protected void add(Message<?> message) {
-        messages.add(message);
-    }
+	/**
+	 * This method determines whether messages have been added to this group
+	 * that supersede the given message based on its sequence id. This can be
+	 * helpful to avoid ending up with sequences larger than their required
+	 * sequence size or sequences that are missing certain sequence numbers.
+	 */
+	public boolean hasNoMessageSuperseding(Message<?> message) {
+		Integer messageSequenceNumber = message.getHeaders().getSequenceNumber();
+		if (messageSequenceNumber != null && messageSequenceNumber > 0) {
+			for (Message<?> member : messages) {
+				Integer memberSequenceNumber = member.getHeaders().getSequenceNumber();
+				if (messageSequenceNumber.equals(memberSequenceNumber)) {
+					return false;
+				}
+			}
+		}
+		return true;
+	}
 
-    /**
-     * {@inheritDoc}
-     */
-    public boolean isComplete() {
-        return completionStrategy.isComplete(messages);
-    }
+	/**
+	 * Add a message to the internal list. This is needed to avoid hitting the
+	 * underlying store or copying the internal list. Use with care.
+	 */
+	protected void add(Message<?> message) {
+		messages.add(message);
+	}
 
-    /**
-     * @return internal message list, modification is allowed, but not recommended
-     */
-    public List<Message<?>> getMessages() {
-        return messages;
-    }
+	public boolean isComplete() {
+		return completionStrategy.isComplete(messages);
+	}
 
-    /**
-     * @return the correlation key that links these messages together according to a particular CorrelationStrategy
-     */
-    public Object getCorrelationKey() {
-        return correlationKey;
-    }
+	/**
+	 * @return internal message list, modification is allowed, but not
+	 *         recommended
+	 */
+	public List<Message<?>> getMessages() {
+		return messages;
+	}
 
-    /**
-     * Call this method to sign off on processing of certain messages e.g. from a MessageProcessor. Typically this will
-     * remove these messages from the processing backlog.
-     */
-    public void onProcessingOf(Message... messages) {
-        for (MessageGroupListener listener : listeners) {
-            listener.onProcessingOf(messages);
-        }
-    }
+	/**
+	 * @return the correlation key that links these messages together according
+	 *         to a particular CorrelationStrategy
+	 */
+	public Object getCorrelationKey() {
+		return correlationKey;
+	}
+
+	/**
+	 * Call this method to sign off on processing of certain messages e.g. from
+	 * a MessageProcessor. Typically this will remove these messages from the
+	 * processing backlog.
+	 */
+	public void onProcessingOf(Message<?>... messages) {
+		for (MessageGroupListener listener : listeners) {
+			listener.onProcessingOf(messages);
+		}
+	}
+
+	/**
+	 * Call this method to signal the completion of the processing of an entire group.
+	 */
+	public void onCompletion() {
+		for (MessageGroupListener listener : listeners) {
+			listener.onCompletionOf(correlationKey);
+		}
+	}
 
-    /**
-     * Call this method to signal the completion of the processing of an entire group
-     */
-    public void onCompletion() {
-        for (MessageGroupListener listener : listeners) {
-            listener.onCompletionOf(correlationKey);
-        }
-    }
 }