docs: public void marshall(User user, ProtocolMarshaller protocolMarshaller) {
  
          if (user == null) {
              throw new SdkClientException("Invalid argument passed to marshall(...)");
          }
  
          try {
              protocolMarshaller.marshall(user.getArn(), ARN_BINDING);
              protocolMarshaller.marshall(user.getUserName(), USERNAME_BINDING);
              protocolMarshaller.marshall(user.getEmail(), EMAIL_BINDING);
              protocolMarshaller.marshall(user.getRole(), ROLE_BINDING);
              protocolMarshaller.marshall(user.getIdentityType(), IDENTITYTYPE_BINDING);
              protocolMarshaller.marshall(user.getActive(), ACTIVE_BINDING);
              protocolMarshaller.marshall(user.getPrincipalId(), PRINCIPALID_BINDING);
          } catch (Exception e) {
              throw new SdkClientException("Unable to marshall request to JSON: " + e.getMessage(), e);
          }
      }