Missing CSRF token causes warning that the content will be executed in restricted mode to be displayed when creating an XClass

Steps to reproduce

1. Login as Admin
2. Go to http://localhost:8080/bin/view/XWiki/XWikiClasses
3. Under 'Create a new data type' section, insert a Title for a new class
4. Click 'Create this Class' button

Expected results

No warning is displayed on the top of the page.

Actual results

The following warning is displayed:

Warning: For security reasons, the 
content of the edited document is executed in restricted mode, as the 
edit was not  initiated by a validated request. There may be unexpected 
errors due to this.

The issue could not be reproduced on XWiki 14.10.6.