code: public function getDefaultRoleInstances()
      {
          $result = [];
          foreach ($this->defaultRoles as $roleName) {
              $result[$roleName] = $this->createRole($roleName);
          }
  
          return $result;
      }
docs: Returns defaultRoles as array of Role objects.
  @since 2.0.12
  @return Role[] default roles. The array is indexed by the role names