Cleanup XML for SelectValues transform

[xdelox]

Fixes #1929

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• [ ] Run mvn clean install apache-rat:check to make sure basic checks pass. A more thorough check will be performed on your pull request automatically.
• [ ] If you have a group of commits related to the same change, please squash your commits into one and force push your branch using git rebase -i.
• [ ] Mention the appropriate issue in your description (for example: addresses #123), if applicable.

To make clear that you license your contribution under the Apache License Version 2.0, January 2004 you have to acknowledge this by using the following check-box.

• [ ] I hereby declare this contribution to be licensed under the Apache License Version 2.0, January 2004
• [ ] In any other case, please file an Apache Individual Contributor License Agreement.