private void addIntVariableBindingCheckForNull(PDU pdu, String oid, Integer val) {
        if (val == null)  {
            pdu.add(new VariableBinding(new OID(oid), new OctetString("null")));
        } else {
            pdu.add(new VariableBinding(new OID(oid),
                    new Integer32(val)));
        }
    }
Adds new {@link VariableBinding} using provided {@link OID} and value to {@link PDU}
if val is null than adds {@link OctetString} with "null" value;
@param pdu
@param oid
@param val
ambari-server/src/main/java/org/apache/ambari/server/notifications/dispatchers/AmbariSNMPDispatcher.java