 present when the transaction has 0 confirmations (or negative confirmations, if conflicted).
  "blockhash" : "hex",                     (string, optional) The block hash containing the transaction.
  "blockheight" : n,                       (numeric, optional) The block height containing the transaction.
  "blockindex" : n,                        (numeric, optional) The index of the transaction in the block that includes it.
  "blocktime" : xxx,                       (numeric, optional) The block time expr