iTunes 12.2 xml file is not present after upgrading my OS X to 10.10.4 and iTunes to 12.2
iTunes 12.2 definitely still generates an iTunes Music Library.xml file. From my machine, running 10.10.4 and iTunes 12.2:


~/Music/iTunes$ ls -l "iTunes Music Library.xml"
-rw-r--r--@ 1 mj  staff  109833070 Jul  2 14:20 iTunes Music Library.xml


That date and time stamp are the date and time I last exited iTunes.

That said, you can recreate the XML file. Apple has document HT201561 that describes the process as well as the purpose of the XML file and when it gets recreated, but note all of the warnings in that document. 

Update: The generation of the XML is now optional in iTunes 12.2 - check Preferences > Advanced and set the option Share iTunes Library XML with other applications