read_tlv_fields!(reader, {
(0, session_priv, required),
(1, payment_id, option),
(2, first_hop_htlc_msat, required),
(3, payment_secret, option),
(4, path, vec_type),
read_tlv_fields!(reader, {
(0, session_priv, required),
(1, payment_id, option),
(2, first_hop_htlc_msat, required),
(3, payment_secret, option),
(4, path, vec_type),