nt is associated with the transaction, only present if not empty.
  "bip125-replaceable" : "str",            (string) ("yes|no|unknown") Whether this transaction signals BIP125 replaceability or has an unconfirmed ancestor signaling BIP125 replaceability.
                                           May be unknown for unconfirmed transactions not in the mempool because their unconfirmed ancestors are unknown.
  "parent_descs" : [                       (json array, optional) Only if 'category' is 'received'. L