title: Appengine spoof User-Agent string
body: <p>I have an internal webservice that allows calls only from particular AppEngine application.
  I'm extracting AppId from User-Agent string however it looks like when I add it multiple times only one will be fixed by Google.</p>
  
  <p>Is there a better way to recognize Appengine application?</p>
  
  <p>My WS is hosted in my network, not at Google.</p>