I can require a field in screens associated with workflow transitions by adding a validator. But since creating an issue isn't a transition, there doesn't seem to be anywhere to add a validator. Instead, there is just a screen scheme where I associate a screen with the 'Create issue' operation.
I can't just mark the field as Required because that would affect other operating units in the company, and they don't want that.
So, how can I require a field in the Create Issue screen for a specific screen scheme?