The pattern translate.xliff.import.ignorableWhitespaceRegex is meant to match those strings, that translators may perceive as empty (and thus, won’t provide a translation for).

The previous pattern:

[\s\p{Z}]*

did not cover, for example, characters of Unicode category “Format”, such as the Zero-Width-Space (ZWSP) character.

We extended the pattern to be also applicable to Unicode categories “Control” and “Format”:

[\s\p{Z}\p{Cc}\p{Cf}]*

Upgrade Notes:

If you haven’t adapted translate.xliff.import.ignorableWhitespaceRegex, no upgrade steps are required.

For any adaptation, you may want to validate, if you want to apply the additional character classes to your pattern as well.

(CMS-26952)