Match field iteration
diff --git a/java_gen/templates/custom/OFMatchV3Ver12.java b/java_gen/templates/custom/OFMatchV3Ver12.java
index a4cc51c..81092c1 100644
--- a/java_gen/templates/custom/OFMatchV3Ver12.java
+++ b/java_gen/templates/custom/OFMatchV3Ver12.java
@@ -106,4 +106,9 @@
         OFOxm<?> oxm = this.oxmList.get(field);
 
         return oxm != null && oxm.isMasked();
-    }
\ No newline at end of file
+    }
+
+    @Override
+    public Iterable<MatchField<?>> getMatchFields() {
+        throw new UnsupportedOperationException();
+    }