docs: public void marshall(DirectMessageConfiguration directMessageConfiguration, ProtocolMarshaller protocolMarshaller) {
  
          if (directMessageConfiguration == null) {
              throw new SdkClientException("Invalid argument passed to marshall(...)");
          }
  
          try {
              protocolMarshaller.marshall(directMessageConfiguration.getADMMessage(), ADMMESSAGE_BINDING);
              protocolMarshaller.marshall(directMessageConfiguration.getAPNSMessage(), APNSMESSAGE_BINDING);
              protocolMarshaller.marshall(directMessageConfiguration.getBaiduMessage(), BAIDUMESSAGE_BINDING);
              protocolMarshaller.marshall(directMessageConfiguration.getDefaultMessage(), DEFAULTMESSAGE_BINDING);
              protocolMarshaller.marshall(directMessageConfiguration.getDefaultPushNotificationMessage(), DEFAULTPUSHNOTIFICATIONMESSAGE_BINDING);
              protocolMarshaller.marshall(directMessageConfiguration.getEmailMessage(), EMAILMESSAGE_BINDING);
              protocolMarshaller.marshall(directMessageConfiguration.getGCMMessage(), GCMMESSAGE_BINDING);
              protocolMarshaller.marshall(directMessageConfiguration.getSMSMessage(), SMSMESSAGE_BINDING);
              protocolMarshaller.marshall(directMessageConfiguration.getVoiceMessage(), VOICEMESSAGE_BINDING);
          } catch (Exception e) {
              throw new SdkClientException("Unable to marshall request to JSON: " + e.getMessage(), e);
          }
      }