public RoundChangeCertificate buildCertificate() {
      return new RoundChangeCertificate(
          roundChangePayloads.stream()
              .map(RoundChange::getSignedPayload)
              .collect(Collectors.toList()));
    }
Build round change certificate.

@return the round change certificate
consensus/ibft/src/main/java/org/hyperledger/besu/consensus/ibft/payload/RoundChangeCertificate.java