Proguard: How to avoid shrinking (and obfuscating) an entire package to avoid removing (and obfuscating) "unused methods"?

Question

I'm currently using an Android library that uses a lot of reflection.

As soon as I enable proguard, and run it... it crashes.

Why? It uses a lot of reflection and the methods are only invoked via reflection, so they are detected by proguard as unused and removed during the shrinking process, so a a NoSuchMethodError is thrown.

Why this happens? That is easy to figure out they are removed during the shrinking process as proguard considers they are unused and therefore removes that pieces of code (all the methods)

So, how can I configure proguard to avoid shrinking or obfuscating an entire package? (the library)

Note: I don't want to use the -dontshrink option, as it's all or nothing and I just want to avoid a specific package.

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More info:

The runtime error is the following:

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.my.app.debug, PID: 3771 
java.lang.NoSuchMethodError: observeValueForKeyPath [class java.lang.String, class java.lang.Object, class com.my.lib.util.Dictionary, class java.lang.Object]
at com.my.lib.util.Observable$ObservationManager$Observer.<init>(SourceFile:47)
at com.my.lib.util.Observable$ObservationManager$Observer.<init>(SourceFile:26)
at com.my.lib.util.Observable$ObservationManager.addObserver(SourceFile:159)
...

Take note that the problem is one an inner inner class...

My current configuration has something like:

-keep,includedescriptorclasses class com.my.** { *; }
-keepclassmembers class com.my.lib** { *; }
-keep,includedescriptorclasses class com.my.lib.util.Observable$* { *; }
-keep,includedescriptorclasses class com.my.lib.util.Observable$*$* { *; }

But this apparently only avoids obfuscating the methods not removed during the shrinking process... I need to avoid removing methods during shrinking.

Answer 1

According to the documentation -keep should work even when shrinking, while -keepclassmembers only works "if [the] classes are preserved as well".