Maps each spent outpoint to the in-mempool transaction that spends it.
Declared in <txmempool.h>
[[guarded_by(0x7fb95f5555b8), guarded_by(0x7fb968bc6cc8), guarded_by(0x7fb95fdd0b08), guarded_by(0x7fb978b75ec8), guarded_by(0x7fb96b8fb428), guarded_by(0x7fb96e5c1ef8), guarded_by(0x7fb97a07bf28), guarded_by(0x7fb96be43c78)]]
indirectmap<COutPoint, txiter> mapNextTx;