Dr. Sun, I'm using your model for HW4 and there's the code below for the user role:

    @ElementCollection
    @CollectionTable(name = "authorities", joinColumns = @JoinColumn(name = "user_id"))
    @Column(name = "role")
    private Set<String> roles;

    ...

    public User() {
        roles = new HashSet<String>();
    }

    public boolean isAdmin() {
        return roles.contains("ROLE_ADMIN");
    }

    public boolean isReviewer() {
        return roles.contains("ROLE_REVIEWER");
    }

I've populated the "authorities" table with user ID and role name, such as (1, 'ROLE_ADMIN'). But when I try to access an admin user's role using the isAdmin() method, it returned a 'false'. Can you give a hint on how to correctly identify the role of a user?