title: Android in-app billing/purchase code copying
body: <p>I'm just about adding in-app billing/purchasing to my android app and read through the official training guide at <a href="http://developer.android.com/training/in-app-billing/preparing-iab-app.html" rel="nofollow">http://developer.android.com/training/in-app-billing/preparing-iab-app.html</a>.</p>
  
  <p>What really surprises me is that fact, that I'm instructed to copy and paste classes from a demo application into my production application.</p>
  
  <p>Is this approach recommended? Undoubtably these helper classes are helpful, but isn't there a dependency I can depend on, so the code is pulled via that? Copying code just doesn't feel right...</p>