When the deadline (deadlineOf) ends and whether it has passed; null with no leg
outstanding, before the clock starts, or for a sweep still inside SWEEP_SETTLE_TIME.
The stale filter returns the transfers whose deadline passed, and no others.
DEBIT legs, oldest posting first. A PENDING transfer holds only the legs attached so far.
The side whose legs total less than the amount on a pending transfer the
operator workflow started, or on an orphaned deposit sweep
(orphanedDepositSweepSql); null on any other transfer.
CREDIT legs, oldest posting first; once COMPLETED they total the same as
debits.