uncomment lines

Signed-off-by: Jiandong Ma <[email protected]>

Author: mjd507

spring-integration-mail/src/main/java/org/springframework/integration/mail/AbstractMailReceiver.java

@@ -652,8 +652,8 @@ public void destroy() {
 		try {
 			closeFolder();
 			MailTransportUtils.closeService(this.store);
-			// this.folder = null;
-			// this.store = null;
+			this.folder = null;
+			this.store = null;
 		}
 		finally {
 			this.folderWriteLock.unlock();