Conditional Expression in JMWE post function

[Bradley Andrikowich]

I'm trying to write a script that sets the "Parent Link" field on an Epic to be that of the Feature Key with the same value, but can't figure out a way to do so. 

We have the below hierarchy in our Jira cloud instance right now as we upgraded to Premium to have an expanded hierarchy:

Feature -> Epic -> Stories -> Subtask

Both a Feature and an Epic contain the same custom field called "Reference Prefix". I would like to set the "Parent Link" field on all Epics to be the Key of the Feature that has the same matching "Reference Prefix" field value.

For example, using the below format:

[Feature Issue Name] | [Reference Prefix Field Value] | [Feature Key]

[Epic Issue Name] | [Reference Prefix Field Value]

• Feature A | ABC-1 | TEST-123
• Epic A | ABC-1
• Epic B | ABC-1
• Epic C | ABC-1

How would I set the Parent Link field to be TEST-123 on all of these epics?

Multiple Epics can map to a single Feature so I'm trying to figure out a script that can apply this kind of logic across multiple issues.