Issue #3242 - Relying on EndPoint.toString() for ProxyEndPoint.toString()

Signed-off-by: Joakim Erdfelt <joakim.erdfelt@gmail.com>

jetty-server/src/main/java/org/eclipse/jetty/server/ProxyConnectionFactory.java

@@ -620,6 +620,11 @@ public class ProxyConnectionFactory extends AbstractConnectionFactory
             return _remote;
         }
 
+        @Override
+        public String toString() {
+            return _endp.toString();
+        }
+
         @Override
         public boolean isOpen()
         {