docs: public Sha256Hash findWitnessCommitment() {
          checkState(isCoinBase());
          for (TransactionOutput out : Lists.reverse(outputs)) {
              Script scriptPubKey = out.getScriptPubKey();
              if (ScriptPattern.isWitnessCommitment(scriptPubKey))
                  return ScriptPattern.extractWitnessCommitmentHash(scriptPubKey);
          }
          return null;
      }