Controller class that calls the Singleton class

SingeltonController.cls

public with sharing class SingeltonController {

    @AuraEnabled
    public static void printDateTime() {
        DateTimeProvider dateProvider = DateTimeProvider.getInstance();
        System.debug('Hey, is it a leap year?');

        Boolean isLeapYear = Date.isLeapYear(dateProvider.now().year());

        if (isLeapYear) {
            System.debug('Yep! Get testing!');
        } else {
            System.debug('All clear. Enjoy your free time :) ');
        }
    }
}