How can you make HTTP Header Dynamic?

For one of my headers (externalReferenceID) I want to make it dynamic to always generate a new string of numbers. First off, is there a simple solution to apply dynamic variables like Postman?

I tried applying this approach in the following link, but it doesn’t seem to be connecting to the test case, any insight what I could be missing?

also here are images below of my following execution.

You can use, for example, ${System.currentTimeMillis}

Thanks huy!!! do I put this in my default -> GlobalVariable (externalReferenceID) and is so value type string?

Hi @mkhan,
Just put it in place of ${externalReferenceID}