How to Implement 'Multiple Project Picker' like 'Multiple Issue Picker'

[nallu]

I have seen field type called 'Multiple Issue Picker' in JIRA. Similarly, I want to implement 'Multiple Project Picker'  custom field. Can anyone please guide me how to do it and where to start?

If there are any documentation that would be really helpful. 

Thanks In Advance!!

[Nic Brough -Adaptavist-]

You will need to write a custom field app to provide this.

Start at https://developer.atlassian.com/server/jira/platform/getting-started/