title: Difference between registerDefaultNetworkCallback and registerNetworkCallback
body: <p>I came across <a href="https://developer.android.com/reference/android/net/ConnectivityManager#registerDefaultNetworkCallback" rel="noreferrer">registerDefaultNetworkCallback</a> and <a href="https://developer.android.com/reference/android/net/ConnectivityManager#registerNetworkCallback" rel="noreferrer">registerNetworkCallback</a> while updating my Android app for API 28.</p>
  
  <p>Having reviewed the documentation, I cannot find the difference between registering a <strong>network callback</strong> and registering a <em>default</em> <strong>network callback</strong>.</p>
  
  <p>When will one use which?</p>
  
  <p>Thanks in advance :)</p>