OFPortDesc: add convenience method to access BsnPortGenerationId
diff --git a/java_gen/templates/custom/OFPortDesc.java b/java_gen/templates/custom/OFPortDesc.java
index 3be1b70..ccfbedb 100644
--- a/java_gen/templates/custom/OFPortDesc.java
+++ b/java_gen/templates/custom/OFPortDesc.java
@@ -8,4 +8,27 @@
     public boolean isEnabled() {
         return (!state.contains(OFPortState.LINK_DOWN) && !config.contains(OFPortConfig.PORT_DOWN));
     }
-    
\ No newline at end of file
+
+    /**
+     * Returns the current generation ID of this port.
+     *
+     * The generationId is reported by the switch as a @{link OFPortDescProp} in
+     * @link{OFPortDescStatsReply} and @link{OFPortStatus} messages. If the
+     * current OFPortDesc does not contain a generation Id, returns U64.ZERO;
+     *
+     * For OpenFlow versions earlier than 1.4, always returns U64.ZERO;
+     *
+     * @return the generation ID or U64.NULL if not reported
+     * @since 1.4
+     */
+     @Nonnull
+     public U64 getBsnGenerationId() {
+         //:: if msg.member_by_name("properties"):
+         for(OFPortDescProp prop: getProperties()) {
+            if(prop instanceof OFPortDescPropBsnGenerationId) {
+                return ((OFPortDescPropBsnGenerationId) prop).getGenerationId();
+            }
+         }
+         //:: #endif
+         return U64.ZERO;
+     }