Your task is to implement a login method in AuthenticationService and findByEmail method in UserService.
More details are described in comments over the methods.
To verify your solution please run main method in Main class. The output in console should be the following:
Test passed for email: bob@i.ua and password 1234
Test passed for email: alice@i.ua and password 1234
Test passed for email: john@i.ua and password 1234
Test passed for email: bob@i.ua and password qwerty
NOTE: please do not modify the Main class.