Scriptrunner - Showing a screen on transition

[Mikhail Kouyantsev]

Hello, everybody.
I'd like to show a cutom screen during a transition. The main point - I don't want to use Behaviors. Let's assume, that in our organization it is highly recomended to keep application changes in code, where it is possible, avoiding any customizations, that cannot be a part of code repository. 
Previously I used Power Scripts and it was a matter of one, barely several lines of code, but I'm unable to find either solution or tutorial regarding Scriptrunner. 
Any help will be welcome.

[Nic Brough -Adaptavist-]

You can do this with a "transition screen" off the shelf, in the workflow.  You don't need any customisations or apps to do that.

[Mikhail Kouyantsev]

Oh, thanks a lot/

But there's a problem - I want to show that screen only when some conditions are met. For example, when I have no issues within specific project, linked with current issue via specific link. 
E.g. when I say "in code" I mean just it ;)
I just can't believe, there's no way to show a screen using lines of code in Scriptrunner.

[Nic Brough -Adaptavist-]

Apps can't get into the hard-coded flow of a workflow to inject anything., but they can inject things into the screens used.  It does do dynamic forms, but I don't know if they are of much use to you (I've not used them so far) - https://scriptrunner.adaptavist.com/latest/jira/dynamic-forms.html

However, I would try the easy way first:

Imagine you have a transition from Dev to Test.  If Alice runs it, they should see Screen-1, but if Bob runs it, they get Screen-2

• Create the transition with Screen-1
• Create a second, parallel transition with Screen-2
• Protect the first one with a condition that says "only Alice can run this", and the second one with "only Bob"

That was a copy and paste of the simple example from my notes and works without scriptrunner.  In your case, you would probably use SR to provide conditions for "no issues in project A linked to B" and the inverse.