fix(example-getting-started): use RestApplication (#955)

- use RestApplication in `example-getting-started` instead of `Application`
- add in `@loopback/openapi-spec` as a dependency in `example-getting-started`

packages/example-getting-started/package.json

@@ -30,6 +30,7 @@
   "dependencies": {
     "@loopback/context": "^4.0.0-alpha.30",
     "@loopback/core": "^4.0.0-alpha.32",
+    "@loopback/openapi-spec": "^4.0.0-alpha.24",
     "@loopback/openapi-v2": "^4.0.0-alpha.9",
     "@loopback/repository": "^4.0.0-alpha.28",
     "@loopback/rest": "^4.0.0-alpha.24",

packages/example-getting-started/src/application.ts

@@ -3,8 +3,8 @@
 // This file is licensed under the MIT License.
 // License text available at https://opensource.org/licenses/MIT
 
-import {Application, ApplicationConfig} from '@loopback/core';
-import {RestComponent} from '@loopback/rest';
+import {ApplicationConfig} from '@loopback/core';
+import {RestApplication} from '@loopback/rest';
 import {TodoController} from './controllers';
 import {TodoRepository} from './repositories';
 import {db} from './datasources/db.datasource';
@@ -18,7 +18,7 @@ import {
   RepositoryMixin,
 } from '@loopback/repository';
 /* tslint:enable:no-unused-imports */
-export class TodoApplication extends RepositoryMixin(Application) {
+export class TodoApplication extends RepositoryMixin(RestApplication) {
   constructor(options?: ApplicationConfig) {
     // TODO(bajtos) The comment below does not make sense to me.
     // Consumers of TodoApplication object should not be changing the shape
@@ -27,14 +27,6 @@ export class TodoApplication extends RepositoryMixin(Application) {
     // which database to connect to, etc.
     // See https://github.com/strongloop/loopback-next/issues/742
 
-    // Allow options to replace the defined components array, if desired.
-    options = Object.assign(
-      {},
-      {
-        components: [RestComponent],
-      },
-      options,
-    );
     super(options);
     this.setupRepositories();
     this.setupControllers();