Add missing @Deprecated annotation

git-svn-id: https://svn.apache.org/repos/asf/mina/ftpserver/trunk@1129715 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/core/src/main/java/org/apache/ftpserver/listener/Listener.java b/core/src/main/java/org/apache/ftpserver/listener/Listener.java
index 99aa033..a5eb918 100644
--- a/core/src/main/java/org/apache/ftpserver/listener/Listener.java
+++ b/core/src/main/java/org/apache/ftpserver/listener/Listener.java
@@ -161,6 +161,7 @@
      *         <code>IpFilterType.DENY</code>. This functionality is provided
      *         for backward compatibility purpose only.
      */
+    @Deprecated
     List<Subnet> getBlockedSubnets();
 
     /**