How to set default value to custom header

Hi ,
I am trying to have a custom header in my spec like below :

- name: 'Client-Type'
in: header
schema:
type: string

**./cli --Client-Type **

I don't want to force user to pass the header like above example command, it should take from spec instead.

So I modified it like below :

- name: 'Client-Type'
in: header
schema:
type: string
default: "my-header"
nullable: true

Still, I don't see this header in my request. And it expects me to pass the same from CLI.

Can you please suggest on this ?

Thanks in advance ;)