Convert examples/distro Gradle build to Kotlin

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

Signed-off-by: Sibasis Padhi <sibasis.padhi@gmail.com>

Author: sibasispadhi

examples/distro/build.gradle

@@ -0,0 +1,88 @@
+group = "io.opentelemetry.example"
+version = "1.0-SNAPSHOT"
+
+buildscript {
+  repositories {
+    maven {
+      url = uri("https://plugins.gradle.org/m2/")
+    }
+    maven {
+      name = "sonatype"
+      url = uri("https://central.sonatype.com/repository/maven-snapshots/")
+    }
+  }
+  dependencies {
+    classpath("com.diffplug.spotless:spotless-plugin-gradle:8.1.0")
+    classpath("com.gradleup.shadow:shadow-gradle-plugin:9.3.1")
+    classpath("io.opentelemetry.instrumentation:gradle-plugins:2.24.0-alpha-SNAPSHOT")
+  }
+}
+
+subprojects {
+  version = rootProject.version
+
+  apply(plugin = "java")
+  apply(plugin = "com.diffplug.spotless")
+
+  val versions = mapOf(
+    // this line is managed by .github/scripts/update-sdk-version.sh
+    "opentelemetrySdk" to "1.57.0",
+
+    // these lines are managed by .github/scripts/update-version.sh
+    "opentelemetryJavaagent" to "2.24.0-SNAPSHOT",
+    "opentelemetryJavaagentAlpha" to "2.24.0-alpha-SNAPSHOT",
+
+    "autoservice" to "1.1.1"
+  )
+
+  val deps = mapOf(
+    "autoservice" to listOf(
+      "com.google.auto.service:auto-service:${versions["autoservice"]}",
+      "com.google.auto.service:auto-service-annotations:${versions["autoservice"]}"
+    )
+  )
+
+  extra["versions"] = versions
+  extra["deps"] = deps
+
+  repositories {
+    mavenCentral()
+    maven {
+      name = "sonatype"
+      url = uri("https://central.sonatype.com/repository/maven-snapshots/")
+    }
+  }
+
+  configure<com.diffplug.gradle.spotless.SpotlessExtension> {
+    java {
+      googleJavaFormat()
+      licenseHeaderFile(rootProject.file("../../buildscripts/spotless.license.java"), "(package|import|public)")
+      target("src/**/*.java")
+    }
+  }
+
+  afterEvaluate {
+    dependencies {
+      add("implementation", platform("io.opentelemetry:opentelemetry-bom:${versions["opentelemetrySdk"]}"))
+
+      // these serve as a test of the instrumentation boms
+      add("implementation", platform("io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom:${versions["opentelemetryJavaagent"]}"))
+      add("implementation", platform("io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom-alpha:${versions["opentelemetryJavaagentAlpha"]}"))
+
+      add("testImplementation", "org.mockito:mockito-core:5.21.0")
+
+      add("testImplementation", enforcedPlatform("org.junit:junit-bom:5.14.2"))
+      add("testImplementation", "org.junit.jupiter:junit-jupiter-api")
+      add("testRuntimeOnly", "org.junit.jupiter:junit-jupiter-engine")
+      add("testRuntimeOnly", "org.junit.platform:junit-platform-launcher")
+    }
+  }
+
+  tasks.named<Test>("test") {
+    useJUnitPlatform()
+  }
+
+  tasks.named<JavaCompile>("compileJava") {
+    options.release.set(8)
+  }
+}