Add timestamp on messages

If the timestamp is not set, clients such as Logstash will tag the
message with the current timestamp when they are consumed.

Change-Id: Ie08a8b2528fdd3f99e33dfd6f52c80ced74d74d3
diff --git a/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/config/AMQProperties.java b/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/config/AMQProperties.java
index 1b87ae5..ecc7c5a 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/config/AMQProperties.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/config/AMQProperties.java
@@ -14,6 +14,7 @@
 
 package com.googlesource.gerrit.plugins.rabbitmq.config;
 
+import com.google.gerrit.server.util.TimeUtil;
 import com.googlesource.gerrit.plugins.rabbitmq.annotation.MessageHeader;
 import com.googlesource.gerrit.plugins.rabbitmq.config.section.Message;
 import com.googlesource.gerrit.plugins.rabbitmq.config.section.Section;
@@ -24,6 +25,7 @@
 import org.slf4j.LoggerFactory;
 
 import java.lang.reflect.Field;
+import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -79,6 +81,7 @@
         .deliveryMode(message.deliveryMode)
         .priority(message.priority)
         .headers(headers)
+        .timestamp(new Date(TimeUtil.nowMs()))
         .build();
     }
     return amqpProperties;