The roles the caller authorizes: exactly the CFX keys the message requires,
or wallet-api refuses SIGNER_MISMATCH. Empty only beside walletId.
OptionalsendBroadcast and follow to commitment once every signer is CFX's.
Base64 wire transaction, every slot empty.
OptionalwalletThe one customer wallet (wal_…) the request acts for; it signs only then.
transaction.create's args: one Solana transaction (packages/wallet-api/README.md).