I recently figured out how to add multiple options in the "Add Parameters to Validator" screen.  

I was not able to figure out how to do this from the example text in  the workflow screen and want to provide a suggestion for changing the text to help the next person trying to add this to their workflow.  Based on the text in the workflow screen (see screenshot), I had tried various permutations of the word "Option" and putting my values in quotes — Option [A,B], [A,B], Option ["A", "B"], "Option [A,B]", etc.

 

JIRA Cloud currently says:  

• Option [A,B] would allow a selection of options: Option A, Option B or both.

Suggestion: 

• (A|B) would allow a selection of options: Option A, Option B or both.

 

Note: I did not validate the "or both" option as my field is a single-select list. I also did not test the other examples for number/character options to determine if parenthesis should be used instead of brackets.

This information would have save me a lot of time and may be a benefit to others.