META-INF/services/<service_file> not being merged properly

[AndrewWestberg]

Expected and Results

I expect that if a service file with the same name is in two different jar files, the contents of these will be combined into the final shadow jar file.

Related environment and versions

gradle 9.1.0 using kotlin build.gradle.kts

Reproduction steps

1.) Step 1: Include io.grpc:grpc-core:1.75.0 in the build.
2.) Step 2: Include io.grpc:grpc-netty:1.75.0 in the build.

Both of these jars contain META-INF/services/io.grpc.NameResolverProvider. The grpc-core contains a DNS Name Resolver Provider. The grpc-netty includes a unix socket Name Resolver Provider.

The final shadow jar contains only the Unix socket name resolver provider and grpc fails due to this.

Anything else?

[AndrewWestberg]

mergeServiceFiles() is being set in the gradle config.

[AndrewWestberg]

duplicatesStrategy = DuplicatesStrategy.INCLUDE
must be set for
mergeServicesFiles()
to work properly. Once this is set, it worked properly.

[bpappin]

This should be noted in the documentation, it took quite a bit of searching to find this.

[Goooler]

It's noted in the doc web and changelogs.

[bpappin]

Not in the section on merging, because I was looking for it.