code: func (r *RoleBindingBuilder) Groups(groups ...string) *RoleBindingBuilder {
  	for _, group := range groups {
  		r.RoleBinding.Subjects = append(r.RoleBinding.Subjects, rbacv1.Subject{Kind: rbacv1.GroupKind, APIGroup: GroupName, Name: group})
  	}
  	return r
  }
docs: // Groups adds the specified groups as the subjects of the RoleBinding.