Kotlin library cause duplicate file error

[JeroenMols]

What version of protobuf and what language are you using?
Version: v3.17.2
Language: Kotlin

What operating system (Linux, Windows, ...) and version?
OSX 11.4

What runtime / compiler are you using (e.g., python version or gcc version)
Protoc version 3.17.2
Gradle version 7.0.2
Android Studio 4.2.1

What did you do?
Steps to reproduce the behavior:

1. Create a new Android studio project
2. Add dependency on com.google.protobuf:protobuf-kotlin:3.17.2
3. Build project
4. See error

What did you expect to see
Project builds successfully

What did you see instead?
Gradle outputs the following error:

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:mergeDebugJavaResource'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.MergeJavaResWorkAction
   > 2 files found with path 'google/protobuf/field_mask.proto' from inputs:
      - /Users/jmols/.gradle/caches/modules-2/files-2.1/com.google.protobuf/protobuf-kotlin/3.17.2/3edd99a5479d55c364eb75027d925ece524e77d5/protobuf-kotlin-3.17.2.jar
      - /Users/jmols/.gradle/caches/modules-2/files-2.1/com.google.protobuf/protobuf-java/3.17.2/d7eec2ad499b605f24d07f49bdcb41c801aafbfc/protobuf-java-3.17.2.jar
     Adding a packagingOptions block may help, please refer to
     https://google.github.io/android-gradle-dsl/current/com.android.build.gradle.internal.dsl.PackagingOptions.html
     for more information

As the error suggests, this is caused because both protobuf-kotlin and protobuf-java include the same *.proto files.

This can be worked around by adding the following to your build.gradle file:

android {
    packagingOptions {
        pickFirst 'google/protobuf/*.proto'
        pickFirst 'google/protobuf/compiler/*.proto'
    }
}

This however is not an option for us as we ship protobuf-kotlin as a transitive dependency in our SDK. Hence this would require all our customers to add this to their build.gradle file, which increases the integration effort or our SDK.

Note: this issue is very similar to #8631, though now the conflict arrises from duplicate .proto files instead of source files.

Anything else we should know about your project / environment

[deannagarcia]

Thanks for reporting this! I am working on a fix and an associated point release.

[JeroenMols]

Verified this on 3.17.3, thanks for the quick fix!