code: public void marshall(HostKeyAttributes hostKeyAttributes, ProtocolMarshaller protocolMarshaller) {
  
          if (hostKeyAttributes == null) {
              throw new SdkClientException("Invalid argument passed to marshall(...)");
          }
  
          try {
              protocolMarshaller.marshall(hostKeyAttributes.getAlgorithm(), ALGORITHM_BINDING);
              protocolMarshaller.marshall(hostKeyAttributes.getPublicKey(), PUBLICKEY_BINDING);
              protocolMarshaller.marshall(hostKeyAttributes.getWitnessedAt(), WITNESSEDAT_BINDING);
              protocolMarshaller.marshall(hostKeyAttributes.getFingerprintSHA1(), FINGERPRINTSHA1_BINDING);
              protocolMarshaller.marshall(hostKeyAttributes.getFingerprintSHA256(), FINGERPRINTSHA256_BINDING);
              protocolMarshaller.marshall(hostKeyAttributes.getNotValidBefore(), NOTVALIDBEFORE_BINDING);
              protocolMarshaller.marshall(hostKeyAttributes.getNotValidAfter(), NOTVALIDAFTER_BINDING);
          } catch (Exception e) {
              throw new SdkClientException("Unable to marshall request to JSON: " + e.getMessage(), e);
          }
      }
docs: Marshall the given parameter object.