Mentions autocomplete can't handle all valid characters in screenNames

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.0.0 DXP GA1, 7.0.0 DXP SP1, Master
• Fix Version/s: 7.0.0 DXP SP1, 7.0.0 DXP FP8, 7.0.3 CE GA4, 7.1.X, Master
• Component/s: Collaboration, Collaboration > Mentions
• Labels:
  • liferay-digital-enterprise-70-sp2
  • liferay-fixpack-de-8-7010
• Branch Version/s:
  7.0.x
• Backported to Branch:
  Committed
• Story Points: 1
• Fix Priority: 3
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/44040

Reproduction steps:

0 - Get DXP vanilla, start it and login as OmniAdmin
1 - Add a user with screenName: some.user
2 - Add a Blogs portlet to a page
3 - Create a blog entry
4 - Start typing: @some.user

Actual behavior: Notice that after you type the dot, the helper is gone
Expected behavior: The on-screen helper should persist even after typing the dot