title: foreground service without notification
body: <p>I want to start a <b>foreground</b> service that doesn't show notification,
  apps like instagram, telegram, zapya, ... have a <strong>foreground service</strong> and they show no notifications.
  I have tested ways like answers 
  <a href="https://stackoverflow.com/q/10962418/6678991">here</a>, but <em>android</em> shows a notification that <code>yourAppName is running</code>.
  I want to know how is that possible to have a foreground service with no notification or warning from OS?</p>