Angular - @Input private field with getters/setters

<!DOCTYPE html>
<html>

  <head>
    <base href="." />
    <title>angular2 playground</title>
    <link rel="stylesheet" href="style.css" />
    <script src="https://unpkg.com/zone.js@0.6.25/dist/zone.js"></script>
    <script src="https://unpkg.com/zone.js@0.6.25/dist/long-stack-trace-zone.js"></script>
    <script src="https://unpkg.com/reflect-metadata@0.1.3/Reflect.js"></script>
    <script src="https://unpkg.com/systemjs@0.19.31/dist/system.js"></script>
    <script src="config.js"></script>
    <script>
    System.import('app')
      .catch(console.error.bind(console));
  </script>
  </head>

  <body>
    <my-app>
    loading...
  </my-app>
  </body>

</html>

/* Styles go here */

### Angular Starter Plunker - Typescript

System.config({
  //use typescript for compilation
  transpiler: 'typescript',
  //typescript compiler options
  typescriptOptions: {
    emitDecoratorMetadata: true
  },
  paths: {
    'npm:': 'https://unpkg.com/'
  },
  //map tells the System loader where to look for things
  map: {
    
    'app': './src',
    
    '@angular/core': 'npm:@angular/core/bundles/core.umd.js',
    '@angular/common': 'npm:@angular/common/bundles/common.umd.js',
    '@angular/compiler': 'npm:@angular/compiler/bundles/compiler.umd.js',
    '@angular/platform-browser': 'npm:@angular/platform-browser/bundles/platform-browser.umd.js',
    '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic.umd.js',
    '@angular/http': 'npm:@angular/http/bundles/http.umd.js',
    '@angular/router': 'npm:@angular/router/bundles/router.umd.js',
    '@angular/forms': 'npm:@angular/forms/bundles/forms.umd.js',
    
    '@angular/core/testing': 'npm:@angular/core/bundles/core-testing.umd.js',
    '@angular/common/testing': 'npm:@angular/common/bundles/common-testing.umd.js',
    '@angular/compiler/testing': 'npm:@angular/compiler/bundles/compiler-testing.umd.js',
    '@angular/platform-browser/testing': 'npm:@angular/platform-browser/bundles/platform-browser-testing.umd.js',
    '@angular/platform-browser-dynamic/testing': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic-testing.umd.js',
    '@angular/http/testing': 'npm:@angular/http/bundles/http-testing.umd.js',
    '@angular/router/testing': 'npm:@angular/router/bundles/router-testing.umd.js',
    
    'rxjs': 'npm:rxjs',
    'typescript': 'npm:typescript@2.0.2/lib/typescript.js'
  },
  //packages defines our app package
  packages: {
    app: {
      main: './main.ts',
      defaultExtension: 'ts'
    },
    rxjs: {
      defaultExtension: 'js'
    }
  }
});

//main entry point
import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';
import {AppModule} from './app.module';

platformBrowserDynamic().bootstrapModule(AppModule)

import {Component, NgModule} from '@angular/core';

@Component({
  selector: 'my-app',
  template: `
    <div>
      <h2>Hello {{name}}</h2>
    </div>
    <user-card [user]="user"></user-card>
  `,
})
export class AppComponent {
  name: string;
  user = {
    name: 'Jenny',
    description: 'A RxJS master'
  };
  constructor() {
    this.name = 'Angular2';
  }
}

//our root app component
import {NgModule} from '@angular/core';
import {BrowserModule} from '@angular/platform-browser';
import {AppComponent} from './app.component';
import {UserCardComponent} from './user-card.component';

@NgModule({
  imports: [ BrowserModule ],
  declarations: [ 
    AppComponent, 
    UserCardComponent 
    ],
  bootstrap: [ AppComponent ]
})
export class AppModule {}

import {Component, Input} from '@angular/core';

@Component({
  selector: 'user-card',
  template: `
    <div>{{user?.name}}</div>
    <p>{{user?.description}}</p>
  `,
  styles: [`
    :host { 
      display: block; 
      border-radius: 4px;
      border: 2px solid #333;
      padding: 6px;
    }
    div { font-weight: bold; }
    p { 
      font-style: italic; 
      margin: 0;
    }
  `]
})
export class UserCardComponent {
  private _user;
  @Input() set user(value) {
    if(value.name === 'Jenny') {
      value.description += `${value.description} *`; 
    }
    this._user = value;
  }
  get user() {
    return this._user;
  }
}