Convert examples/distro Gradle build to Kotlin

[sibasispadhi]

Migrate examples/distro/build.gradle from Groovy to Kotlin DSL for improved consistency with the rest of the repository.

Most of the instrumentation repository (608 files) already uses Kotlin for Gradle build files. This migration converts one of the remaining Groovy files to match the established pattern.

Fixes #15794

[linux-foundation-easycla]

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• ✅ login: sibasispadhi / name: Sibasis Padhi (667d7e9, 96c3cfd, 9ebde93, c9650ed)

[jaydeluca]

there is a merge conflict that needs to be resolved, in case you didn't see

[sibasispadhi]

@jaydeluca kindly review.

[jaydeluca]

@jaydeluca kindly review.

Regarding the add("implementation", ...) syntax: inside plugins.withType { dependencies { } }, the Kotlin DSL doesn't provide the extension functions directly, so add() is the idiomatic approach for deferred configuration (consistent with how other Kotlin DSL builds handle this pattern).

are you sure? I don't see anything about that mentioned in the docs https://docs.gradle.org/current/kotlin-dsl/gradle/org.gradle.api.artifacts.dsl/-dependency-handler/index.html

I'm also not sure you even need plugins.withType {?

I would think you could simplify this to just

  dependencies {
    implementation(platform("io.opentelemetry:opentelemetry-bom:${versions.getValue("opentelemetrySdk")}"))

    implementation(platform("io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom:${versions.getValue("opentelemetryJavaagent")}"))
    implementation(platform("io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom-alpha:${versions.getValue("opentelemetryJavaagentAlpha")}"))

    testImplementation("org.mockito:mockito-core:5.21.0")

    testImplementation(enforcedPlatform("org.junit:junit-bom:5.14.2"))
    testImplementation("org.junit.jupiter:junit-jupiter-api")
    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine")
    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
  }

  tasks.test {
    useJUnitPlatform()
  }

  tasks.compileJava {
    options.release.set(8)
  }

but perhaps you could try it out

[sibasispadhi]

@jaydeluca
After some trial and error, I discovered that the dependency extension functions
(implementation(), testImplementation()) aren't available inside plugins.withId()
callbacks in a subprojects block; this is a Kotlin DSL scoping limitation.

Final solution:

• Used add() inside plugins.withId("java") { dependencies { } }
• Moved task configuration outside using tasks.named() for type safety
• Kept getValue() for safer map access

This hybrid approach gives us deferred configuration where needed (dependencies) and type safety where possible (tasks). Thanks for pushing me to explore different approaches. I definitely learned more about Kotlin DSL scoping through this!