These methods allow to perform actions based on the entity before the
CRUD operation is executed.

Additionally moved previously missed v2 entities to the v2 package.

The new overloaded patch methods applies changes to a field instead of
the whole entity. The field is specified with a method reference to the
getter.

Implemented a patch method which merges an existing entity with updated
properties from a HashMap. A new test dependency spring-security-test
has been added.