user role config info hook

backdrop_test_users.php

<?php
/**
 * Implements hook_config_info().
 */
function backdrop_test_users_config_info() {
  $prefixes = array();

  $prefixes['user.role.developer'] = array(
    'name_key' => 'name',
    'label_key' => 'label',
    'group' => t('User roles'),
  );
  $prefixes['user.role.site_owner'] = array(
    'name_key' => 'name',
    'label_key' => 'label',
    'group' => t('User roles'),
  );
  return $prefixes;
}