Returning ChangeHistory string as a Version - Scripted Field

[Rebecca Ebersol]

I have a custom scripted field using Scriptrunner that returns the "Planned Fix Version" for a JIRA epic.  In order to do this, I have to traverse the ChangeHistory for the issue, and the change history stores the value the field changes to as a string.  However, I want to return this value as a Version.

I haven't figured out how to do this.  I tried doing a "as Version", but that doesn't seem to be working.  I can provide code snippets if necessary. 

Thanks.