R8 raise warning that there are missing classes while optimizing

[ganadist]

What version of gRPC-Java are you using?

• 1.54.0

What is your environment?

• OS : Any
• Jdk : OpenJDK 11 / 17
• Gradle 8.0.2
• Android Gradle Plugin 7.4.2 / 8.0.0
• Kotlin 1.7.21

What did you expect to see?

• Android App build can be succeed

What did you see instead?

• App build is failed with following warnings / errors

                                         buffers
:app:minifyProductionReleaseWithR8 FAILED
WARNING: app/build/intermediates/merged_java_res/productionRelease/base.jar: 
ERROR:Missing classes detected while running R8. 
Please add the missing classes or apply additional keep rules that are generated in app/build/outputs/mapping/productionRelease/missing_rules.txt.
This will become an error in AGP 8.0.   
ERROR:R8: 
Missing class javax.naming.NamingEnumeration (referenced from: void io.grpc.internal.JndiResourceResolverFactory$JndiRecordFetcher.closeThenThrow(javax.naming.NamingEnumeration, javax.naming.NamingException) and 1 other context)  
Missing class javax.naming.NamingException (referenced from: void io.grpc.internal.JndiResourceResolverFactory$JndiRecordFetcher.closeThenThrow(javax.naming.NamingEnumeration, javax.naming.NamingException) and 4 other contexts)
Missing class javax.naming.directory.Attribute (referenced from: java.util.List io.grpc.internal.JndiResourceResolverFactory$JndiRecordFetcher.getAllRecords(java.lang.String, java.lang.String))       
Missing class javax.naming.directory.Attributes (referenced from: java.util.List io.grpc.internal.JndiResourceResolverFactory$JndiRecordFetcher.getAllRecords(java.lang.String, java.lang.String))      
Missing class javax.naming.directory.DirContext (referenced from: void io.grpc.internal.JndiResourceResolverFactory$JndiRecordFetcher.closeThenThrow(javax.naming.directory.DirContext, javax.naming.NamingException) and 1 other context)      
Missing class javax.naming.directory.InitialDirContext (referenced from: java.util.List io.grpc.internal.JndiResourceResolverFactory$JndiRecordFetcher.getAllRecords(java.lang.String, java.lang.String))       
~

Workaround

Add following rules for missing classes

-dontwarn javax.naming.NamingEnumeration
-dontwarn javax.naming.NamingException
-dontwarn javax.naming.directory.Attribute
-dontwarn javax.naming.directory.Attributes
-dontwarn javax.naming.directory.DirContext
-dontwarn javax.naming.directory.InitialDirContext

• It seems gRPC-java provides proguard rules for android platform, and above rules should be added for AGP 8.0

Steps to reproduce the bug

[JaySyntax]

For me, after upgrading to AGP 8, i was still having the issue, so what i did next was to add this two different rules to my proguard (.pro) rules and it worked.

1. -dontwarn okhttp3.internal.platform.** -dontwarn org.conscrypt.** -dontwarn org.bouncycastle.** -dontwarn org.openjsse.**

2. -dontwarn com.google.protobuf.java_com_google_android_gmscore_sdk_target_granule__proguard_group_gtm_N1281923064GeneratedExtensionRegistryLite**

3. -keep,allowobfuscation,allowshrinking class kotlin.coroutines.Continuation

note: i got this from here