Displaying Deviniti Bundled Field value in Scripted Field?

[Zita Bagi]

Based on https://deviniti.com/support/addon/server/extension/latest/use-data-from-bundled-fields-in-script-runner-ver67/ I'm trying to find out how to copy the value of a bundled custom field cell into a ScriptRunner. It's a Text Field (single line), contains a number (as string), and I need to grab its value.
I'm not sure which part of https://deviniti.com/support/addon/server/extension/latest/use-data-from-bundled-fields-in-script-runner-ver67/ I have to use or how to use issueEvent.getIssue() to always refer to the current issue and not to a specific one.
Basically we have different tabs on the view screen, one tab has bundled fields, and I would like to display the value of a bundled field in a Scripted Field on another tab.
Is this something you can advise me on?

Thank you!

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[Paul Wright]

I do find it worrying that 604 people have viewed this question (presumably looking for some guidance) and there are no comments are it was posted Feb 2020.  :( 

Should I be fortunate enough to find the answer, I will share it here!