Extended choice parameters - How to use Groovy Script File in Jenkins parameterized job

Can you show example of how to use file in git. Do you use fuel command in the groovy script? Or can we read file in pervious build workspace?

I am trying to use property file in "Extended Choice Parameter" > "JSON Parameter Type" > JSON Parameter Config Groovy Script.
Here, next to header, I want checkbox. How to do so?

Hi AJ, I have question about groovy script file. Can i place the groovy script file in github repo and can access the file from jenkins extended choice parameter

This is an eye opener.

Thanks a ton!