How to get external task custom attributes



My requirement is like this.

I have created one workflow and few external tasks there. When process start and it find there is an external task then I can get notify at the event I defined outside of camunda. Using below code used for .net

public class CamundaTaskHandler : ExternalTaskHandler
public override async Task Process(ExternalTask externalTask)
// this object “externalTask” has all the variables which are there in REST API of external task.

Now I want to send some custom attributes or fields like “Role” and it’s values Admin. For another task “Role” and it’s value “Manager”.

How can I implement? I tried to pass variables using “Extensions” --> Add Property option, but I didn’t get it anywhere in above handle.

My basic need is external project is not aware about process of camunda. Just task start and it will have some properties from which external project will do some process and once that task is finished, again call one method (REST API) to say camunda that this task is complete.

Thanks in advance