try reconnecting after link properties changed

In some circumstances (like the server only being reachable over IPv6)
reconnecting when the network becomes available doesn't work. This due
to the network only being "partially" available (in the example: IPv4
working, but IPv6 not yet). By also listening for changes of the link
properties a new connection attempt is made when for example the IP
addresses of the link, or the networking routes change. Meaning that the
example issue is fixed, as a new attempt is made after the IPv6 address
is set on the link / the routes for IPv6 networking are available.

Author: Robert Meijers

app/src/main/kotlin/com/github/gotify/service/WebSocketService.kt

@@ -9,6 +9,7 @@ import android.content.Intent
 import android.content.pm.ServiceInfo
 import android.graphics.Color
 import android.net.ConnectivityManager
+import android.net.LinkProperties
 import android.net.Network
 import android.os.Build
 import android.os.IBinder
@@ -57,6 +58,12 @@ internal class WebSocketService : Service() {
                 Logger.info("WebSocket: Network available, reconnect if needed.")
                 connection?.start()
             }
+
+            override fun onLinkPropertiesChanged(network: Network, linkProperties: LinkProperties) {
+                super.onLinkPropertiesChanged(network, linkProperties)
+                Logger.info("WebSocket: Network properties changed, reconnect if needed.")
+                connection?.start()
+            }
         }
     private val appIdToApp = ConcurrentHashMap<Long, Application>()