NullPointerException in servlet instrumentation (AsyncListener)

[pellmont]

Describe the bug
We are doing long polling through an async Endpoint. Due to misconfiguration of our client the client had a timeout before the server sent a response. This led to a NullPointerException in Servlet3Accessor:

The following uncaught exception was thrown by the AsyncListener: [io.opentelemetry.javaagent.instrumentation.servlet.v3_0.Servlet3Accessor$Listener] during onComplete: [java.lang.NullPointerException: Cannot invoke "javax.servlet.http.HttpServletResponse.isCommitted()" because "response" is null at io.opentelemetry.javaagent.instrumentation.servlet.v3_0.Servlet3Accessor.isResponseCommitted(Servlet3Accessor.java:70) at io.opentelemetry.javaagent.instrumentation.servlet.v3_0.Servlet3Accessor.isResponseCommitted(Servlet3Accessor.java:19) at io.opentelemetry.javaagent.instrumentation.servlet.ServletHttpAttributesGetter.statusCode(ServletHttpAttributesGetter.java:72) at io.opentelemetry.javaagent.instrumentation.servlet.ServletHttpAttributesGetter.statusCode(ServletHttpAttributesGetter.java:12) at io.opentelemetry.javaagent.shaded.instrumentation.api.instrumenter.http.HttpCommonAttributesExtractor.onEnd(HttpCommonAttributesExtractor.java:65) at io.opentelemetry.javaagent.shaded.instrumentation.api.instrumenter.http.HttpServerAttributesExtractor.onEnd(HttpServerAttributesExtractor.java:132) at io.opentelemetry.javaagent.shaded.instrumentation.api.instrumenter.Instrumenter.doEnd(Instrumenter.java:224) at io.opentelemetry.javaagent.shaded.instrumentation.api.instrumenter.Instrumenter.end(Instrumenter.java:144) at io.opentelemetry.javaagent.instrumentation.servlet.AsyncRequestCompletionListener.onComplete(AsyncRequestCompletionListener.java:37) at io.opentelemetry.javaagent.instrumentation.servlet.v3_0.Servlet3Accessor$Listener.onComplete(Servlet3Accessor.java:82) at com.ibm.ws.webcontainer.async.AsyncListenerEntry.invokeOnComplete(AsyncListenerEntry.java:87) at com.ibm.ws.webcontainer.async.CompleteRunnable.invokeOnComplete(CompleteRunnable.java:94) at com.ibm.ws.webcontainer.async.CompleteRunnable.run(CompleteRunnable.java:57) at com.ibm.ws.webcontainer.async.ServiceWrapper.wrapAndRun(ServiceWrapper.java:236) at com.ibm.ws.webcontainer.async.ContextWrapper.run(ContextWrapper.java:28) at com.ibm.ws.threading.internal.ExecutorServiceImpl$RunnableWrapper.run(ExecutorServiceImpl.java:245) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) at java.base/java.lang.Thread.run(Thread.java:833) ]

This seems to be caused by an AsyncEvent without a response object (which seems to be the case on dropped connections at least in recent openliberty server releases)

The result is a missing span (and therefore a invalid parent span in the trace).

Servlet5Accessor seems to have the same problemn, too (although I didn't verify that)

What version are you using?
v1.19.2