Add @since tag

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1063211 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/http/proxy/src/main/java/org/apache/felix/http/proxy/ProxyListener.java b/http/proxy/src/main/java/org/apache/felix/http/proxy/ProxyListener.java
index 95b7760..f615552 100644
--- a/http/proxy/src/main/java/org/apache/felix/http/proxy/ProxyListener.java
+++ b/http/proxy/src/main/java/org/apache/felix/http/proxy/ProxyListener.java
@@ -39,6 +39,8 @@
  * The <code>ProxyListener</code> implements a Servlet API listener for HTTP
  * Session related events. These events are provided by the servlet container
  * and forwarded to the event dispatcher.
+ *
+ * @since 2.1.0
  */
 public class ProxyListener implements HttpSessionAttributeListener, HttpSessionListener, ServletContextListener
 {