(2, HighZeroBytesDroppedBigSize(payload.amt_to_forward), required),
(4, HighZeroBytesDroppedBigSize(payload.outgoing_cltv_value), required),
(6, short_channel_id, required)
(2, HighZeroBytesDroppedBigSize(payload.amt_to_forward), required),
(4, HighZeroBytesDroppedBigSize(payload.outgoing_cltv_value), required),
(6, short_channel_id, required)