chore(demo): make Android channel ID configurable

Author: fadi-george

examples/demo/.env.example

@@ -2,3 +2,7 @@
 ONESIGNAL_APP_ID=your-onesignal-app-id
 ONESIGNAL_API_KEY=your_rest_api_key
 E2E_MODE=false
+
+# Optional: Android Notification Channel ID for the WITH SOUND test notification.
+# Create one in your OneSignal dashboard under Settings > Android Notification Categories.
+ONESIGNAL_ANDROID_CHANNEL_ID=

examples/demo/Services/OneSignalApiService.cs

@@ -6,6 +6,8 @@ namespace OneSignalDemo.Services;
 
 public class OneSignalApiService
 {
+    private const string DefaultAndroidChannelId = "b3b015d9-c050-4042-8548-dcc34aa44aa4";
+
     private string _appId = "";
 
     public void SetAppId(string appId) => _appId = appId;
@@ -20,6 +22,12 @@ public bool HasApiKey()
 
     private string GetApiKey() => DotEnv.Get("ONESIGNAL_API_KEY");
 
+    private static string GetAndroidChannelId()
+    {
+        var value = DotEnv.Get("ONESIGNAL_ANDROID_CHANNEL_ID")?.Trim();
+        return string.IsNullOrEmpty(value) ? DefaultAndroidChannelId : value;
+    }
+
     public async Task<bool> SendNotificationAsync(NotificationType type, string subscriptionId)
     {
         try
@@ -55,7 +63,7 @@ public async Task<bool> SendNotificationAsync(NotificationType type, string subs
                     extra = new Dictionary<string, object>
                     {
                         ["ios_sound"] = "vine_boom.wav",
-                        ["android_channel_id"] = "b3b015d9-c050-4042-8548-dcc34aa44aa4",
+                        ["android_channel_id"] = GetAndroidChannelId(),
                     };
                     break;
                 default: