Add ugly hacky oreo notification support

android/app/src/main/java/de/gotify/UglyHackyOreoNotificationCompatibilitySupport.java

@@ -0,0 +1,48 @@
+package de.gotify;
+
+
+import android.app.NotificationManager;
+import android.os.Build;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+
+/**
+ * I hate reflections and android.
+ */
+public class UglyHackyOreoNotificationCompatibilitySupport {
+    public static final String CHANNEL_ID = "gotify";
+
+    /**
+     * @param notificationManager the notification manager
+     * @see <a href="https://stackoverflow.com/a/48861133/4244993">Code by Elad Nava</a>
+     */
+    public static void uglyInitializeNotificationChannel(NotificationManager notificationManager) {
+        if (Build.VERSION.SDK_INT < 26) {
+            return;
+        }
+
+        // Channel importance (3 means default importance)
+        int channelImportance = 3;
+
+        try {
+            // Get NotificationChannel class via reflection (only available on devices running Android O or newer)
+            Class notificationChannelClass = Class.forName("android.app.NotificationChannel");
+
+            // Get NotificationChannel constructor
+            Constructor<?> notificationChannelConstructor = notificationChannelClass.getDeclaredConstructor(String.class, CharSequence.class, int.class);
+
+            // Instantiate new notification channel
+            Object notificationChannel = notificationChannelConstructor.newInstance(CHANNEL_ID, "Gotify", channelImportance);
+
+            // Get notification channel creation method via reflection
+            Method createNotificationChannelMethod = notificationManager.getClass().getDeclaredMethod("createNotificationChannel", notificationChannelClass);
+
+            // Invoke method on NotificationManager, passing in the channel object
+            createNotificationChannelMethod.invoke(notificationManager, notificationChannel);
+
+        } catch (Exception e) {
+            Log.e("Creating notification channel failed.", e);
+        }
+    }
+}