AEM 5.6 login problem - username is case-sensitive
After upgrade from CQ5 to AEM 5.6.1 our authoring environment stopped authorizing users with usernames provided with incorrect case, i.e. if we have a user record with ID Firstname.Lastname system will refuse logging user in as firstname.lastname . We are using Active Directory integration and it worked well in CQ5.
Any ideas how to fix this and make usernames acceptable in any case?