Bugfix/minification proguard missing symbols

[Yousif-CS]

A customer ran into an issue when enabling minification and encountered the following crash:

No pending exception expected: java.lang.ClassNotFoundException: kotlin.ULong 
  at java.lang.String java.lang.Runtime.nativeLoad(java.lang.String, java.lang.ClassLoader, java.lang.Class) (Runtime.java:-2) 
  at void java.lang.Runtime.loadLibrary0(java.lang.ClassLoader, java.lang.Class, java.lang.String) (Runtime.java:1095) 
  at void java.lang.Runtime.loadLibrary0(java.lang.Class, java.lang.String) (Runtime.java:1019) 
  at void java.lang.System.loadLibrary(java.lang.String) (System.java:1765) at void com.millicast.Core.initialize() (SourceFile:14) 
  at void com.theoplayer.android.internal.millicast.b.<clinit>() (SourceFile:9) at

This requires integrating applications to add a keep rule for kotlin.* classes in their proguard file. This PR introduces it for the example application, enables minification for release builds by default and also adds a note in the documentation.

[Copilot]

Pull request overview

Updates the example Android app and Millicast documentation to address a crash seen when enabling minification (missing Kotlin classes at runtime).

Changes:

• Add a ProGuard/R8 keep rule for kotlin.* to the example app.
• Enable minification for example Android release builds by default.
• Document the required keep rule in doc/millicast.md.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
example/android/app/proguard-rules.pro	Adds a keep rule intended to prevent Kotlin classes from being stripped during minification.
example/android/app/build.gradle	Enables ProGuard/R8 minification for release builds in the example app.
doc/millicast.md	Documents the Android minification note and keep rule for Millicast integration.

[Copilot]

-keep class kotlin.** { *; } disables shrinking/obfuscation for the entire Kotlin stdlib, which can significantly reduce the benefit of enabling minification (larger APK/AAB). Consider narrowing this rule to only the specific Kotlin classes that are reflectively/JNI-referenced (e.g., the unsigned types involved in the crash) so release builds still get meaningful shrinking.

Suggested change

	-keep class kotlin.** { *; }
	# Keep only specific Kotlin stdlib classes that are reflectively/JNI-referenced
	-keep class kotlin.UInt { *; }
	-keep class kotlin.ULong { *; }
	-keep class kotlin.UByte { *; }
	-keep class kotlin.UShort { *; }

[Copilot]

This documentation asks integrators to manually add a ProGuard/R8 keep rule, but the library already publishes consumer rules via consumerProguardFiles (see android/build.gradle). To prevent production crashes when minification is enabled, consider shipping the necessary keep rule(s) in the library’s consumer ProGuard file instead of relying on every app to add a manual rule.

Suggested change

	When adding the Millicast integration into your android project, make sure to add the following keep rule in your `proguard-rules.pro` file:
	```
	-keep class kotlin.** { *; }
	```
	Otherwise, you will encounter a `ClassNotFoundException` when attempting to run the application.
	The Millicast integration ships its required ProGuard/R8 keep rules via the library's `consumerProguardFiles` configuration.
	In a typical setup, no additional ProGuard/R8 rules are needed to use Millicast with minification enabled.
	If you use a heavily customized ProGuard/R8 configuration, ensure that the consumer rules from the library are not being overridden or removed, otherwise you may encounter `ClassNotFoundException` errors at runtime.

[tvanlaerhoven]

@Yousif-CS wouldn't it make more sense to add the R8 rules to the Millicast's consumer rules as is suggested here? Otherwise all Millicast SDK customers will have to include these rules I guess?

[Yousif-CS]

I think we can, though from what I've seen in the docs it needs to be added at the app level? Let me try that.

[Copilot]

Capitalize “Android” for consistency with the rest of the docs ("your Android project").

Suggested change

	When adding the Millicast integration into your android project, make sure to add the following keep rule in your `proguard-rules.pro` file:
	When adding the Millicast integration into your Android project, make sure to add the following keep rule in your `proguard-rules.pro` file: