feat: equals and hashcode for role

import javax.persistence.ManyToMany;

import javax.persistence.Table;

import javax.validation.constraints.NotBlank;

import java.util.Objects;

import java.util.Set;

@Entity

    @ManyToMany(mappedBy = "roles")

    private Set<User> users;

    @Override

    public boolean equals(Object o) {

        if (this == o) return true;

        if (!(o instanceof Role)) return false;

        Role role = (Role) o;

        return Objects.equals(getName(), role.getName());

    }

    @Override

    public int hashCode() {

        return Objects.hash(getName());

    }

}