code: public void marshall(Update update, ProtocolMarshaller protocolMarshaller) {
  
          if (update == null) {
              throw new SdkClientException("Invalid argument passed to marshall(...)");
          }
  
          try {
              protocolMarshaller.marshall(update.getKey(), KEY_BINDING);
              protocolMarshaller.marshall(update.getUpdateExpression(), UPDATEEXPRESSION_BINDING);
              protocolMarshaller.marshall(update.getTableName(), TABLENAME_BINDING);
              protocolMarshaller.marshall(update.getConditionExpression(), CONDITIONEXPRESSION_BINDING);
              protocolMarshaller.marshall(update.getExpressionAttributeNames(), EXPRESSIONATTRIBUTENAMES_BINDING);
              protocolMarshaller.marshall(update.getExpressionAttributeValues(), EXPRESSIONATTRIBUTEVALUES_BINDING);
              protocolMarshaller.marshall(update.getReturnValuesOnConditionCheckFailure(), RETURNVALUESONCONDITIONCHECKFAILURE_BINDING);
          } catch (Exception e) {
              throw new SdkClientException("Unable to marshall request to JSON: " + e.getMessage(), e);
          }
      }
docs: Marshall the given parameter object.