System of Librarian Equation

Java Spring Boot + PostgresSQL + HTML/CSS + Bootstrap 4

The system is designed for the management of the library.
There are three roles in the system:
the administrator.
The Employee.
the user.
The Adnister:
He can do everything.
Add / remove / edit data about employees, books, users and their belonging to books (which they took to read)
The Employee.
You can add/release/edit user and book data.
Also to issue or receive the books back.
the user.
You can only take or return the book.
Registration in the system is only possible as a user.
Employees are added only by the administrator.
The system keeps the account of all users (all roles), all books (accessible, which are on hand)
And it shows everything in the web interface.