OptionalchainChain ID for the payment chain. Required by mppx client. Defaults to Tempo Moderato (4217) when absent.
OptionaldecimalsToken decimals. Required by mppx client to build Tempo Transactions.
OptionalmethodMethod-specific extra details (e.g. feePayer flag, splits, memo).
mppx encodes these under methodDetails in the challenge request.
Decoded MPP challenge request object