From d6c334bb1c287b21e3894b259e7d7d5d70693a18 Mon Sep 17 00:00:00 2001
From: Andrea Marziali <andrea.marziali@datadoghq.com>
Date: Wed, 3 Jun 2026 10:53:54 +0200
Subject: [PATCH] Tolerate servlet 2.x wrappers used on servlet-3 classpath for
 isAsyncStarted calls

---
 .../instrumentation/servlet3/Servlet3Advice.java |  6 +++---
 .../servlet3/Servlet3Decorator.java              | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/dd-java-agent/instrumentation/servlet/javax-servlet/javax-servlet-3.0/src/main/java/datadog/trace/instrumentation/servlet3/Servlet3Advice.java b/dd-java-agent/instrumentation/servlet/javax-servlet/javax-servlet-3.0/src/main/java/datadog/trace/instrumentation/servlet3/Servlet3Advice.java
index c750c3fafc1..43ff802600c 100644
--- a/dd-java-agent/instrumentation/servlet/javax-servlet/javax-servlet-3.0/src/main/java/datadog/trace/instrumentation/servlet3/Servlet3Advice.java
+++ b/dd-java-agent/instrumentation/servlet/javax-servlet/javax-servlet-3.0/src/main/java/datadog/trace/instrumentation/servlet3/Servlet3Advice.java
@@ -158,7 +158,7 @@ public static void stopSpan(
 
       final AgentSpan span = spanFromContext(scope.context());
 
-      if (request.isAsyncStarted()) {
+      if (DECORATE.safeIsAsyncStarted(request)) {
         AtomicBoolean activated = new AtomicBoolean();
         FinishAsyncDispatchListener asyncListener =
             new FinishAsyncDispatchListener(scope, activated, !isDispatch);
@@ -166,11 +166,11 @@ public static void stopSpan(
         request.setAttribute(DD_FIN_DISP_LIST_SPAN_ATTRIBUTE, asyncListener);
         try {
           request.getAsyncContext().addListener(asyncListener);
-        } catch (final IllegalStateException e) {
+        } catch (final IllegalStateException | AbstractMethodError ignored) {
           // org.eclipse.jetty.server.Request may throw an exception here if request became
           // finished after check above. We just ignore that exception and move on.
         }
-        if (!request.isAsyncStarted() && activated.compareAndSet(false, true)) {
+        if (!DECORATE.safeIsAsyncStarted(request) && activated.compareAndSet(false, true)) {
           if (!isDispatch) {
             DECORATE.onResponse(span, resp);
           }
diff --git a/dd-java-agent/instrumentation/servlet/javax-servlet/javax-servlet-3.0/src/main/java/datadog/trace/instrumentation/servlet3/Servlet3Decorator.java b/dd-java-agent/instrumentation/servlet/javax-servlet/javax-servlet-3.0/src/main/java/datadog/trace/instrumentation/servlet3/Servlet3Decorator.java
index 9db2d47d437..67332c5b581 100644
--- a/dd-java-agent/instrumentation/servlet/javax-servlet/javax-servlet-3.0/src/main/java/datadog/trace/instrumentation/servlet3/Servlet3Decorator.java
+++ b/dd-java-agent/instrumentation/servlet/javax-servlet/javax-servlet-3.0/src/main/java/datadog/trace/instrumentation/servlet3/Servlet3Decorator.java
@@ -10,6 +10,7 @@
 import datadog.trace.bootstrap.instrumentation.api.UTF8BytesString;
 import datadog.trace.bootstrap.instrumentation.decorator.HttpServerDecorator;
 import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.slf4j.Logger;
@@ -127,4 +128,19 @@ public AgentSpan onError(final AgentSpan span, final Throwable throwable) {
     }
     return span;
   }
+
+  /**
+   * Safely calls ServletRequest#isAsyncStarted. Some 2.x wrappers might be dangling in the 3.x
+   * classpath and produce an AbstractMethodError
+   *
+   * @param servletRequest the servlet request.
+   * @return the real call result or false when the method does not exist in the provided object.
+   */
+  public boolean safeIsAsyncStarted(final ServletRequest servletRequest) {
+    try {
+      return servletRequest.isAsyncStarted();
+    } catch (AbstractMethodError ignored) {
+      return false;
+    }
+  }
 }