Can Hibernate ever force any constraints on table columns?

Question

Here's what I want Hibernate to do

First, to check the existence of the required table. If it's absent, create it according to my schema.sql file. If it's present, update it according to the code in the @Entity class

Second, fill the users tables with sample rows if it's empty and ensure the roles table has at least a row with role = 'USER' and a row with role = 'ADMIN'. Also, fill the @JoinTable in case users was filled with my sample rows

To do that, I added these properties in my application.properties file

# url, username, password

spring.jpa.hibernate.ddl-auto=update
spring.jpa.defer-datasource-initialization=true
spring.sql.init.mode=always

and put schema.sql and data.sql files in my resources/sql directory

# schema.sql

CREATE TABLE users
(
    id         INT          NOT NULL AUTO_INCREMENT,
    username   VARCHAR(15)  NOT NULL UNIQUE,
    password   VARCHAR(200) NOT NULL,
    name       VARCHAR(15)  NOT NULL,
    last_name  VARCHAR(25)  NOT NULL,
    department VARCHAR(50)  NOT NULL,
    salary     INT,
    age        TINYINT      NOT NULL,
    email      VARCHAR(50),
    enabled    TINYINT      NOT NULL,
    PRIMARY KEY (id)
);

CREATE TABLE roles
(
    id   INT         NOT NULL AUTO_INCREMENT,
    role VARCHAR(15) NOT NULL UNIQUE,
    PRIMARY KEY (id)
);

CREATE TABLE user_role
(
    user_id  INT         NOT NULL,
    username VARCHAR(15) NOT NULL,
    role_id  INT         NOT NULL,
    role     VARCHAR(15) NOT NULL,
    PRIMARY KEY (user_id, role_id),
    FOREIGN KEY (user_id) REFERENCES users (id),
    FOREIGN KEY (role_id) REFERENCES roles (id)
);

INSERT INTO users(username, password, name, last_name, department, salary, age, email, enabled)
SELECT *
FROM (VALUES ('mickey_m', '$2y$10$i5SJc2KAriHGn7Dz2rRQHuQ3JfBxlzMaPVKP1YdEJCukryDY9NbVC',
              'Mickey', 'Mouse', 'sales', 180000, 95, 'mickey_m@gmail.com', 1),

              # and so on

               ) sample_rows

WHERE NOT EXISTS(SELECT NULL FROM users);

INSERT IGNORE INTO roles(role)
VALUES ('USER'),
       ('ADMIN');

INSERT IGNORE INTO user_role (user_id, username, role_id, role)
SELECT users.id, users.username, roles.id, roles.role
FROM (VALUES
          ROW ('mickey_m', 'USER'),
          ROW ('scrooge_m', 'USER'),
          ROW('scrooge_m', 'ADMIN')
          # and so on
     )
     AS user_to_role (username, role)
     JOIN users ON users.username = user_to_role.username
     JOIN roles ON roles.role = user_to_role.role;

Now, it doesn't seem to work. At least, Hibernate is fine with the fact that my columns are mostly nullable. It doesn't force them to become NOT NULL. The @Entity classes match schema.sql in terms of nullability

@Entity
@Table(name = "users")
public class User implements UserDetails {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    @Column(nullable = false, unique = true)
    private String username;
    @Column(nullable = false)
    private String password;
// and so on

I don't get any error messages

How do I make Hibernate alter tables according to my @Entity mappings?