Guide/Approach for Jira Plugin Development to make a custom field as required/mandatory

Hi All,
Recently we have started with plugin development for our Jira Instance.
Currently we are developing plugin for a requirement in which we want to make a custom field as required/mandatory. I have following query related to this:

1.) Is there a rest API for making a custom field mandatory… How to make a field required or optional using jir...

2.)is there a plugin already available by which we can set a custom field as mandatory?
https://marketplace.atlassian.com/search?hosting=dataCenter&product=jira&query=Custom%20fields

3.)Also, please let us know if there is any programmatic way todo it apart from writing custom behavior scripts to achieve the same.

I’m new to Jira plugin development and It will be very helpful if you can guide me around possible approaches/tools and share information around above queries.

Thanks,
Rishabh