Generate opt-in instrumentation version class

conventions/src/main/kotlin/io/opentelemetry/instrumentation/gradle/GenerateInstrumentationVersionClassTask.kt

@@ -0,0 +1,52 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.gradle
+
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.TaskAction
+
+abstract class GenerateInstrumentationVersionClassTask : DefaultTask() {
+  @get:Input
+  abstract val className: Property<String>
+
+  @get:Input
+  abstract val instrumentationVersion: Property<String>
+
+  @get:OutputDirectory
+  abstract val outputDirectory: DirectoryProperty
+
+  @TaskAction
+  fun generate() {
+    val configuredClassName = className.get()
+    val lastDotIndex = configuredClassName.lastIndexOf('.')
+    require(lastDotIndex > 0 && lastDotIndex < configuredClassName.length - 1) {
+      "instrumentationVersionClass.className must be a fully qualified class name"
+    }
+
+    val packageName = configuredClassName.substring(0, lastDotIndex)
+    val simpleClassName = configuredClassName.substring(lastDotIndex + 1)
+    val outputRoot = outputDirectory.get().asFile
+    outputRoot.deleteRecursively()
+    val outputDir = outputRoot.resolve(packageName.replace('.', '/'))
+    outputDir.mkdirs()
+    outputDir.resolve("$simpleClassName.java").writeText(
+      """
+      package $packageName;
+
+      /** Autogenerated class. Do not edit. */
+      public final class $simpleClassName {
+        public static final String VERSION = "${instrumentationVersion.get()}";
+
+        private $simpleClassName() {}
+      }
+      """.trimIndent()
+    )
+  }
+}

conventions/src/main/kotlin/io/opentelemetry/instrumentation/gradle/InstrumentationVersionClassExtension.kt

@@ -0,0 +1,12 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.gradle
+
+import org.gradle.api.provider.Property
+
+abstract class InstrumentationVersionClassExtension {
+  abstract val className: Property<String>
+}

conventions/src/main/kotlin/otel.instrumentation-version-class.gradle.kts

@@ -0,0 +1,33 @@
+import io.opentelemetry.instrumentation.gradle.GenerateInstrumentationVersionClassTask
+import io.opentelemetry.instrumentation.gradle.InstrumentationVersionClassExtension
+
+plugins {
+  `java-library`
+}
+
+val instrumentationVersionClass = extensions.create<InstrumentationVersionClassExtension>("instrumentationVersionClass")
+val generatedInstrumentationVersionClassDir = layout.buildDirectory.dir("generated/sources/instrumentationVersionClass/java/main")
+
+val generateInstrumentationVersionClass by tasks.registering(GenerateInstrumentationVersionClassTask::class) {
+  className.set(instrumentationVersionClass.className)
+  instrumentationVersion.set(project.version.toString())
+  outputDirectory.set(generatedInstrumentationVersionClassDir)
+}
+
+sourceSets {
+  main {
+    java {
+      srcDir(generatedInstrumentationVersionClassDir)
+    }
+  }
+}
+
+tasks.matching {
+  it.name == "compileJava" || it.name == "sourcesJar" || it.name == "compileKotlin" || it.name == "kotlinSourcesJar"
+}.configureEach {
+  dependsOn(generateInstrumentationVersionClass)
+}
+
+tasks.withType<Checkstyle>().matching { it.name == "checkstyleMain" }.configureEach {
+  exclude("build/generated/sources/instrumentationVersionClass/java/main/**")
+}

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/InstrumenterBuilder.java

@@ -96,8 +96,6 @@ public final class InstrumenterBuilder<REQUEST, RESPONSE> {
     this.openTelemetry = openTelemetry;
     this.instrumentationName = instrumentationName;
     this.spanNameExtractor = spanNameExtractor;
-    this.instrumentationVersion =
-        EmbeddedInstrumentationProperties.findVersion(instrumentationName);
   }
 
   /**
@@ -304,6 +302,10 @@ private Instrumenter<REQUEST, RESPONSE> buildInstrumenter(
 
     applyCustomizers(this);
 
+    if (instrumentationVersion == null) {
+      instrumentationVersion = EmbeddedInstrumentationProperties.findVersion(instrumentationName);
+    }
+
     this.spanKindExtractor = spanKindExtractor;
     return constructor.create(this);
   }

instrumentation/okhttp/okhttp-3.0/library/build.gradle.kts

@@ -1,9 +1,14 @@
 plugins {
   id("otel.library-instrumentation")
+  id("otel.instrumentation-version-class")
   id("otel.nullaway-conventions")
   id("otel.animalsniffer-conventions")
 }
 
+instrumentationVersionClass {
+  className.set("io.opentelemetry.instrumentation.okhttp.v3_0.internal.InstrumentationVersion")
+}
+
 dependencies {
   compileOnly(project(":muzzle"))
   compileOnly("com.squareup.okhttp3:okhttp:3.11.0")

instrumentation/okhttp/okhttp-3.0/library/src/main/java/io/opentelemetry/instrumentation/okhttp/v3_0/internal/OkHttpClientInstrumenterBuilderFactory.java

@@ -20,7 +20,9 @@ public class OkHttpClientInstrumenterBuilderFactory {
   public static DefaultHttpClientInstrumenterBuilder<Interceptor.Chain, Response> create(
       OpenTelemetry openTelemetry) {
     return DefaultHttpClientInstrumenterBuilder.create(
-        INSTRUMENTATION_NAME, openTelemetry, new OkHttpAttributesGetter());
+            INSTRUMENTATION_NAME, openTelemetry, new OkHttpAttributesGetter())
+        .setBuilderCustomizer(
+            builder -> builder.setInstrumentationVersion(InstrumentationVersion.VERSION));
   }
 
   private OkHttpClientInstrumenterBuilderFactory() {}