Maps each spent outpoint to the in-mempool transaction that spends it.
Declared in <txmempool.h>
[[guarded_by(0x7f2e1b5a1a88), guarded_by(0x7f2e2721aa98), guarded_by(0x7f2e421cc1a8), guarded_by(0x7f2e2880b168), guarded_by(0x7f2e3212e4f8), guarded_by(0x7f2e347f6b88), guarded_by(0x7f2e2b05aff8), guarded_by(0x7f2e2bee2698)]]
indirectmap<COutPoint, txiter> mapNextTx;