title: Service receive null Intent without START_STICKY flag
body: <p>I have a Service that manages different types of Intents.</p>
  
  <p>Depending on the Intent it's managing it returns START_REDELIVER_INTENT or START_NOT_STICKY.</p>
  
  <p>It never returns START_STICKY.
  So I put an assert (intent != null) at the begin of onStartCommand.</p>
  
  <p>Anyway, from Firebase crashreports I see that it happened few times and on different Android version.</p>
  
  <p>I do NOT send null intents to the Service in all my code and I've never seen it happen in all my tests.</p>
  
  <p>Does anyone know when it should happen?
  I've not found any evidence in Service documentation.</p>
  
  <p>Thanks</p>