[Android] ClassNotFoundException for UMP classes if obfuscation is enabled

[256p]

[REQUIRED] Step 1: Describe your environment

• Unity version: 2023.2.3f1
• Google Mobile Ads Unity plugin version: 8.6.0
• Platform: Android
• Platform OS version: All versions
• Any specific devices issue occurs on: Any device
• Mediation ad networks used, and their versions: no mediated ad networks

[REQUIRED] Step 2: Describe the problem

Steps to reproduce:

1. Create new project and import Google Mobile Ads Plugin
2. Implement UMP consent pop-up
3. In Project Setting -> Player -> Publishing Settings -> Minify enable minification
4. Build and run
5. Consent pop-up will not show and in the logcat will be error:

   AndroidJavaException: java.lang.ClassNotFoundException: com.google.android.ump.UserMessagingPlatform
   java.lang.ClassNotFoundException: com.google.android.ump.UserMessagingPlatform
   at java.lang.Class.classForName(Native Method)
   at java.lang.Class.forName(Class.java:536)
   Caused by: java.lang.ClassNotFoundException: com.google.android.ump.UserMessagingPlatform
   ... 2 more
   at UnityEngine.AndroidJNISafe.CheckException () [0x00000] in <00000000000000000000000000000000>:0 
   at UnityEngine.AndroidJNISafe.FindClass (System.String name) [0x00000] in <00000000000000000000000000000000>:0 
   at UnityEngine.AndroidJavaClass._AndroidJavaClass (System.String className) [0x00000] in <00000000000000000000000000000000>:0 
   at GoogleMobileAds.Ump.Android.ConsentInformationClient..ctor () [0x00000] in <00000000000000000000000000000000>:0 
   at GoogleMobileAds.Ump.Android.ConsentInformationClient..cctor () [0x00000] in <00000000000000000000000000000000>:0 
   at GoogleMobileAds.Ump.Android.UmpClientFactory.ConsentInformation

Relevant Code:

https://github.com/256p/ump-class-not-found

The reason of the issue is that UMP's Java classes are accessed from C# through reflection, and these Java classes aren't added to the Proguard rules to preserve them from obfuscation. All class names (except com.google.unity.ump.*) listed here https://github.com/googleads/googleads-mobile-unity/blob/main/source/plugin/Assets/GoogleMobileAds/Ump/Platforms/Android/Utils.cs aren't accessible after obfuscation. Probably need to add native bridging UMP implementation to the android-library.

[NVentimiglia]

Thanks, we will look into this issue.

[amjaliks]

@256p, add to proguard-user.txt:

-keep class com.google.android.ump.** { public *; }

@NVentimiglia, it would be useful to include a note about Proguard/R8 in the implementation documentation.

[NVentimiglia]

Thanks,

We will look into this.

[NVentimiglia]

Confirming the issue. If you use magnification please add a custom proguard file.

-keep class com.google.** { public *; }

[batteredhedgehog]

@NVentimiglia .. there isn't a whole lot of point using minification if you're going to put rules like that into proguard. The purpose is to slim down your build by removing unneeded code. Can someone suggest a set of less inclusive proguard rules for using admob?

[NVentimiglia]

@batteredhedgehog you can try

 -keep class com.google.android.ump.** { public *; }