Fix for AMQ-1616: we should not be throwing an exception if close() is called twice.

git-svn-id: https://svn.apache.org/repos/asf/activemq/trunk@645601 13f79535-47bb-0310-9956-ffa450edef68

activemq-core/src/main/java/org/apache/activemq/ActiveMQConnection.java

@@ -546,8 +546,6 @@ public class ActiveMQConnection implements Connection, TopicConnection, QueueCon
      *                 cause this exception to be thrown.
      */
     public void close() throws JMSException {
-        checkClosed();
-
         try {
             // If we were running, lets stop first.
             stop();