How to use the ember-runtime.readOnly function in ember-runtime

The Routing service is used by LinkComponent, and provides facilities for
  the component/view layer to interact with the router.

  This is a private service for internal usage only. For public usage,
  refer to the `Router` service.

  @private
  @class RoutingService
*/
export default Service.extend({
  router: null,

  targetState: readOnly('router.targetState'),
  currentState: readOnly('router.currentState'),
  currentRouteName: readOnly('router.currentRouteName'),
  currentPath: readOnly('router.currentPath'),

  hasRoute(routeName) {
    return get(this, 'router').hasRoute(routeName);
  },

  transitionTo(routeName, models, queryParams, shouldReplace) {
    let router = get(this, 'router');

    let transition = router._doTransition(routeName, models, queryParams);

    if (shouldReplace) {
      transition.method('replace');
    }

    return transition;
  },

/**
  The Routing service is used by LinkComponent, and provides facilities for
  the component/view layer to interact with the router.

  This is a private service for internal usage only. For public usage,
  refer to the `Router` service.

  @private
  @class RoutingService
*/
export default Service.extend({
  router: null,

  targetState: readOnly('router.targetState'),
  currentState: readOnly('router.currentState'),
  currentRouteName: readOnly('router.currentRouteName'),
  currentPath: readOnly('router.currentPath'),

  hasRoute(routeName) {
    return get(this, 'router').hasRoute(routeName);
  },

  transitionTo(routeName, models, queryParams, shouldReplace) {
    let router = get(this, 'router');

    let transition = router._doTransition(routeName, models, queryParams);

    if (shouldReplace) {
      transition.method('replace');
    }

    return transition;

import { routeArgs } from '../utils';

/**
  The Routing service is used by LinkComponent, and provides facilities for
  the component/view layer to interact with the router.

  This is a private service for internal usage only. For public usage,
  refer to the `Router` service.

  @private
  @class RoutingService
*/
export default Service.extend({
  router: null,

  targetState: readOnly('router.targetState'),
  currentState: readOnly('router.currentState'),
  currentRouteName: readOnly('router.currentRouteName'),
  currentPath: readOnly('router.currentPath'),

  hasRoute(routeName) {
    return get(this, 'router').hasRoute(routeName);
  },

  transitionTo(routeName, models, queryParams, shouldReplace) {
    let router = get(this, 'router');

    let transition = router._doTransition(routeName, models, queryParams);

    if (shouldReplace) {
      transition.method('replace');
    }

/**
  The Routing service is used by LinkComponent, and provides facilities for
  the component/view layer to interact with the router.

  This is a private service for internal usage only. For public usage,
  refer to the `Router` service.

  @private
  @class RoutingService
*/
export default Service.extend({
  router: null,

  targetState: readOnly('router.targetState'),
  currentState: readOnly('router.currentState'),
  currentRouteName: readOnly('router.currentRouteName'),
  currentPath: readOnly('router.currentPath'),

  hasRoute(routeName) {
    return get(this, 'router').hasRoute(routeName);
  },

  transitionTo(routeName, models, queryParams, shouldReplace) {
    let router = get(this, 'router');

    let transition = router._doTransition(routeName, models, queryParams);

    if (shouldReplace) {
      transition.method('replace');
    }