Scripted validator that checks values of two fields

[Willis Towers Watson Atlassian Team]

Here's my situation:

I have an issue type where a single select field has identical values to that of the initial field in a subsequent cascading select. I need a scripted validator that prevents a workflow transition if those two values don't match. I'm not very groovy savvy at all, and I've hit a wall looking at the various snippets Scriptrunner provides. Any help out there?