Author of https://github.com/andygrunwald/go-jira here:

This lib is maintained, still a bit out of date and has a few flaws. Like using the same client for JIRA Cloud and JIRA OnPremise (different APIs). But most of the flaws have been evolved over time, while Atlassian switched strategies.

I am preparing a roadmap for v2 where I implement a lot of reliability features, like context support, but also separate APIs for OnPremise and Cloud and easier access for custom fields.

Watch the github repo if you want to stay up to date.