Fixed a bug that caused flows without instructions/actions (i.e. drop flows)...

Fixed a bug that caused flows without instructions/actions (i.e. drop flows) to throw an exception during serialization. This addresses an issue common to the SFP and the switch flow stats reply serialization (since they both rely on the same core.web serializer).

src/main/java/net/floodlightcontroller/core/web/serializers/OFInstructionListSerializer.java

@@ -74,7 +74,7 @@ public class OFInstructionListSerializer extends JsonSerializer<List<OFInstructi
                 } // end switch on instruction
                 jGen.writeEndObject(); // end specific instruction
             } // end for instructions
-            jGen.writeEndObject();
         } // end process instructions (OF1.1+ only)
+        jGen.writeEndObject(); // end object (either has instructions or a "none":"drop" key:value as specified above)
     } // end not-empty instructions (else)
 }