META-INF/version duplicate error when using Proguard

Question

Gradle : 4.10.1 Gradle Android Plugin version : 3.3.2 Proguard : 6.0.3 JDK - 1.9 Android Studio 3.3.2 When I try to build apk release version along with Proguard. I get the following error -

Caused by: java.io.IOException: Please correct the above warnings first.
    at proguard.InputReader.execute(InputReader.java:149)
    at proguard.ProGuard.readInput(ProGuard.java:255)
    at proguard.ProGuard.execute(ProGuard.java:96)
    ......

This seems to be caused due to this -

Warning: class [META-INF/versions/9/module-info.class] unexpectedly contains class [module-info]
Note: duplicate definition of program class [module-info]
Note: there were 20 duplicate class definitions.
      (http://proguard.sourceforge.net/manual/troubleshooting.html#duplicateclass)
Warning: there were 21 classes in incorrectly named files.
         You should make sure all file names correspond to their class names.
         The directory hierarchies must correspond to the package hierarchies.

From extensive searching it looks like Proguard has a problem with META-INF/versions/9. I have multiple dependencies that contain this.

While the issue to seems to somewhat documented, no solutions prescribed seem to work. https://sourceforge.net/p/proguard/bugs/665/ suggests filtering out those class files via -

-injars my_lib.jar(!META-INF/versions/**.class)

However when I try this it just labels more files as duplicate and incorrectly named. I also tried excluding it via gradle-

packagingOptions {
        exclude 'META-INF/DEPENDENCIES'
        exclude 'META-INF/DEPENDENCIES.txt'
        exclude 'META-INF/LICENSE'
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/license.txt'
        exclude 'META-INF/NOTICE'
        exclude 'META-INF/NOTICE.txt'
        exclude 'META-INF/notice.txt'
        exclude 'META-INF/INDEX.LIST'
        exclude 'META-INF/versions'
        exclude 'META-INF/versions/9/module-info.class'
   }

This also fails to resolve the problem. How do I solve this problem ?

Answer 1

I realise this is a very old question, but I was able to get this to work using this gradle configuration:

task obfuscate(type: proguard.gradle.ProGuardTask) {
    configuration files("proguard-project.txt")
    libraryjars files("build/rt.jar", "build/jce.jar")
    injars files("build/libs/desktop-${version}.jar"), filter: "!META-INF/versions/**/*.class"
    outjars files("build/libs/obfuscated.jar")
}

I think the issue with the injars directive you used might be the path - should be META-INF/versions/**/*.class.