[TECH. SUPPORT] LPS-32188

Hi Mate,

While I was trying to fix LPS-32187, I stumbled upon some regression bugs in Private Messaging Portlet. In order to be able to fix the original XSS issue, I had to deal with them first.

* Deploying Private Messaging Portlet ends up in JSP compilation error caused by laszlocsontos/liferay-portal@a94e0d1.

Thanks for reviewing.

Cheers,
Laci.

PS: Pull request for LPS-32187 is coming soon.