Merge into master from pull request #226:
ICMPv4Type and ICMPv4Code cannot be converted into TransportPort. Thus, ... (https://github.com/floodlight/loxigen/pull/226)
diff --git a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/ArpOpcode.java b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/ArpOpcode.java
index 10d8add..dd50d29 100644
--- a/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/ArpOpcode.java
+++ b/java_gen/pre-written/src/main/java/org/projectfloodlight/openflow/types/ArpOpcode.java
@@ -191,4 +191,8 @@
         sink.putShort((short) this.opcode);
     }
 
-}
\ No newline at end of file
+    @Override
+    public String toString() {
+        return String.valueOf(this.opcode);
+    }
+}