Appointment scheduler

This is a Spring Boot Web Application to manage and schedule appointments between providers and customers. It has many features such as automatic invoicing, email notifications, appointment cancelation, providers' individual working plans with breaks etc. Admin can add new providers, services and assign services to providers. Admin can see list of all: appointments, providers, customers, and invoices. He can also issue invoices manually for all confirmed appointments. The provider can set his own working plan, add breaks to that working plan and change his available services. The provider sees only his own appointments. After the appointment status is changed to the finished system automatically sends an email to the customer with information that appointment is finished. In case the appointment didn't take place there is also a link attached to that email that allows customers to reject that the appointment didn't take place.