code: public function addRole($role)
      {
          if (is_string($role)) {
              $role = new Role($role);
          } elseif (!$role instanceof RoleInterface) {
              throw new \InvalidArgumentException(sprintf('Role must be a string or RoleInterface instance, but got %s.', gettype($role)));
          }
          
          if(!\in_array($role, $this->roles)) {
              $this->roles[] = $role;
          }
      }
docs: Add user role.