Fix ktor3 latest dep test

Author: laurit

instrumentation/ktor/ktor-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/ktor/v3_0/ServerInstrumentation.java

@@ -10,13 +10,16 @@
 
 import io.ktor.server.application.Application;
 import io.ktor.server.application.ApplicationPluginKt;
+import io.ktor.server.engine.EmbeddedServer;
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.instrumentation.ktor.v2_0.common.AbstractKtorServerTelemetryBuilder;
 import io.opentelemetry.instrumentation.ktor.v2_0.common.internal.KtorBuilderUtil;
 import io.opentelemetry.instrumentation.ktor.v3_0.KtorServerTelemetryBuilderKt;
 import io.opentelemetry.javaagent.bootstrap.internal.AgentCommonConfig;
 import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
 import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
 import kotlin.Unit;
 import kotlin.jvm.functions.Function1;
 import net.bytebuddy.asm.Advice;
@@ -39,7 +42,18 @@ public void transform(TypeTransformer transformer) {
   public static class ConstructorAdvice {
 
     @Advice.OnMethodExit
-    public static void onExit(@Advice.FieldValue("_applicationInstance") Application application) {
+    public static void onExit(
+        @Advice.This EmbeddedServer<?, ?> server, @Advice.Origin MethodHandles.Lookup lookup)
+        throws Throwable {
+      MethodHandle getter;
+      try {
+        // since 3.0.3
+        getter = lookup.findGetter(EmbeddedServer.class, "applicationInstance", Application.class);
+      } catch (NoSuchFieldException exception) {
+        // before 3.0.3
+        getter = lookup.findGetter(EmbeddedServer.class, "_applicationInstance", Application.class);
+      }
+      Application application = (Application) getter.invoke(server);
       ApplicationPluginKt.install(
           application, KtorServerTelemetryBuilderKt.getKtorServerTelemetry(), new SetupFunction());
     }