The mentioned method is also changed to only retrieve http header
informations instead of whole URI content.

Added TODOs to keep track of methods still evicting the whole answers
cache for future improvements. Additional refactoring is necessary to
implement these.

Direct method calls bypass the caching proxy if AspectJ weaving is not
configured.

At least caching of learning progress responses
did not work since commit a59eb75f on March, 6th.

While the exact origin of this problem is unclear,
it seemed like Spring was creating more than one
databaseDao bean. One of these beans had no
working caching annotations.

These events add more detail about what specific
action just happened.

Unlock is a better representation because this event only
occurs when multiple questions are published. 'New' should
only be used when questions are created.

Check user object against null before accepting feedback via Websocket.

See:
http://docs.spring.io/spring-security/site/migrate/current/3-to-4/html5/migrate-3-to-4-jc.html#m3to4-header-jc
http://docs.spring.io/spring-security/site/migrate/current/3-to-4/html5/migrate-3-to-4-jc.html#m3to4-filter-urls-cas

Task #15666
Task #15693