How do I use regex to convert number to string in a formula column of a structure board?

[Pavan Cheruvu]

Hi : This is the scenario, where I need help. I am using a formula column to sort and pick the latest fixversion.  The fixVersion are stored as "YY.MM.DD" and can have multiple values.

I am taking the strings in fixVersion and converting to a number, by removing the decimal. 

I than sort and pick the highest value. 

----------------

fixVersions

  .map(v -> v.name.replace(".", ""))

  .sortBy(v -> -v)

  .first()

-------------------------------

I now want to add the decimal back to the highest value, before displaying in the structure board.

I have tried various combinations like
.map(v -> v.replace(("\\d{2})(\\d{2})(\\d{2})", "$1.$2.$3"))

but it is not working!

Regards, Pavan