`mergeServiceFiles()` does not work as expected when using `DuplicatesStrategy.EXCLUDE`

[ketan]

Expected and Results

Here's a snippet of code that had some unexpected results:

plugins {
    id 'java-library'
    id("com.gradleup.shadow") version("9.0.0-beta10")
}

repositories {
    mavenCentral()
}

dependencies {
    implementation("io.grpc:grpc-netty-shaded:1.63.0")
    implementation("io.grpc:grpc-core:1.63.0")

}

shadowJar {
    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
    mergeServiceFiles()
}

I was expecting that this would remove any duplicate files introduced between the 2 libs that I'm shadowing, but merge the service files.

Apparently, service files don't "merge" because duplicates are being excluded. Removing the DuplicatesStrategy.EXCLUDE seems to properly merge the service files.

In the above case, look for the file META-INF/services/io.grpc.NameResolverProvider in the generated jar.

Related environent and versions

Java:

openjdk version "17.0.14" 2025-01-21
OpenJDK Runtime Environment Temurin-17.0.14+7 (build 17.0.14+7)
OpenJDK 64-Bit Server VM Temurin-17.0.14+7 (build 17.0.14+7, mixed mode, sharing)

H/W:

mac mini m4 running macOS 15.3.2

Reproduction steps

No response

Anything else?

No response

[Goooler]

This is the correct behavior. The duplicatesStrategy takes precedence over transforming and relocating.

[Goooler]

There are other choices provided in #1553 and #1682.

See the details in https://gradleup.com/shadow/configuration/merging/#handling-duplicates-strategy