Added Message expiration property to header.

spring-eai-core/src/main/java/org/springframework/eai/message/MessageHeader.java

@@ -16,6 +16,7 @@
 
 package org.springframework.eai.message;
 
+import java.util.Date;
 import java.util.Map;
 import java.util.Properties;
 import java.util.concurrent.ConcurrentHashMap;
@@ -38,6 +39,8 @@ public class MessageHeader {
 
 	private String replyChannelName;
 
+	private Date expiration;
+
 	private int sequenceNumber = 1;
 
 	private int sequenceSize = 1;
@@ -76,6 +79,22 @@ public class MessageHeader {
 		return this.sequenceNumber;
 	}
 
+	/**
+	 * Set the expiration date for this message or <code>null</code>
+	 * to indicate 'never expire'. The default is <code>null</code>.
+	 */
+	public void setExpiration(Date expiration) {
+		this.expiration = expiration;
+	}
+
+	/**
+	 * Return the expiration date for this message or
+	 * <code>null</code> to indicate 'never expire'.
+	 */
+	public Date getExpiration() {
+		return this.expiration;
+	}
+
 	public void setSequenceNumber(int sequenceNumber) {
 		this.sequenceNumber = sequenceNumber;
 	}