code: func (s *OrganizationsService) ListOutsideCollaborators(ctx context.Context, org string, opt *ListOutsideCollaboratorsOptions) ([]*User, *Response, error) {
  	u := fmt.Sprintf("orgs/%v/outside_collaborators", org)
  	u, err := addOptions(u, opt)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	var members []*User
  	resp, err := s.client.Do(ctx, req, &members)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return members, resp, nil
  }
docs: // ListOutsideCollaborators lists outside collaborators of organization's repositories.
  // This will only work if the authenticated
  // user is an owner of the organization.
  //
  // Warning: The API may change without advance notice during the preview period.
  // Preview features are not supported for production use.
  //
  // GitHub API docs: https://developer.github.com/v3/orgs/outside_collaborators/#list-outside-collaborators