fix liberty extractor

instrumentation/liberty/compile-stub/src/main/java/com/ibm/ws/http/dispatcher/internal/channel/HttpDispatcherLink.java

@@ -5,6 +5,8 @@
 
 package com.ibm.ws.http.dispatcher.internal.channel;
 
+import com.ibm.wsspi.http.HttpResponse;
+
 // https://github.com/OpenLiberty/open-liberty/blob/master/dev/com.ibm.ws.transport.http/src/com/ibm/ws/http/dispatcher/internal/channel/HttpDispatcherLink.java
 public class HttpDispatcherLink {
 
@@ -27,4 +29,8 @@ public String getRequestedHost() {
   public int getRequestedPort() {
     throw new UnsupportedOperationException();
   }
+
+  public HttpResponse getResponse() {
+    throw new UnsupportedOperationException();
+  }
 }

instrumentation/liberty/compile-stub/src/main/java/com/ibm/wsspi/http/HttpResponse.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.ibm.wsspi.http;
+
+import java.util.List;
+
+// https://github.com/OpenLiberty/open-liberty/blob/integration/dev/com.ibm.ws.transport.http/src/com/ibm/wsspi/http/HttpResponse.java
+public interface HttpResponse {
+
+  List<String> getHeaders(String name);
+}

instrumentation/liberty/compile-stub/src/main/java/com/ibm/wsspi/http/channel/HttpRequestMessage.java

@@ -15,6 +15,8 @@ public interface HttpRequestMessage {
 
   HeaderField getHeader(String paramString);
 
+  List<HeaderField> getHeaders(String name);
+
   String getScheme();
 
   String getRequestURI();

instrumentation/liberty/liberty-dispatcher/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/liberty/dispatcher/LibertyDispatcherHttpAttributesExtractor.java

@@ -6,14 +6,16 @@
 package io.opentelemetry.javaagent.instrumentation.liberty.dispatcher;
 
 import io.opentelemetry.instrumentation.api.instrumenter.http.HttpServerAttributesExtractor;
+import io.opentelemetry.javaagent.instrumentation.api.config.HttpHeadersConfig;
+import java.util.List;
 import org.checkerframework.checker.nullness.qual.Nullable;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 public class LibertyDispatcherHttpAttributesExtractor
     extends HttpServerAttributesExtractor<LibertyRequest, LibertyResponse> {
-  private static final Logger logger =
-      LoggerFactory.getLogger(LibertyDispatcherHttpAttributesExtractor.class);
+
+  public LibertyDispatcherHttpAttributesExtractor() {
+    super(HttpHeadersConfig.capturedServerHeaders());
+  }
 
   @Override
   protected @Nullable String method(LibertyRequest libertyRequest) {
@@ -25,6 +27,11 @@ public class LibertyDispatcherHttpAttributesExtractor
     return libertyRequest.getHeaderValue("User-Agent");
   }
 
+  @Override
+  protected List<String> requestHeader(LibertyRequest libertyRequest, String name) {
+    return libertyRequest.getHeaderValues(name);
+  }
+
   @Override
   protected @Nullable Long requestContentLength(
       LibertyRequest libertyRequest, @Nullable LibertyResponse libertyResponse) {
@@ -67,6 +74,12 @@ public class LibertyDispatcherHttpAttributesExtractor
     return null;
   }
 
+  @Override
+  protected List<String> responseHeader(
+      LibertyRequest libertyRequest, LibertyResponse libertyResponse, String name) {
+    return libertyResponse.getHeaderValues(name);
+  }
+
   @Override
   protected @Nullable String target(LibertyRequest libertyRequest) {
     String requestUri = libertyRequest.getRequestUri();

instrumentation/liberty/liberty-dispatcher/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/liberty/dispatcher/LibertyDispatcherLinkInstrumentation.java

@@ -68,6 +68,7 @@ public static void onEnter(
 
     @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
     public static void stopSpan(
+        @Advice.This HttpDispatcherLink httpDispatcherLink,
         @Advice.Thrown Throwable throwable,
         @Advice.Argument(value = 0) StatusCodes statusCode,
         @Advice.Argument(value = 2) Exception failure,
@@ -79,7 +80,7 @@ public static void stopSpan(
       }
       scope.close();
 
-      LibertyResponse response = new LibertyResponse(statusCode);
+      LibertyResponse response = new LibertyResponse(httpDispatcherLink, statusCode);
       request.setCompleted();
 
       Throwable t = failure != null ? failure : throwable;

instrumentation/liberty/liberty-dispatcher/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/liberty/dispatcher/LibertyRequest.java

@@ -8,6 +8,8 @@
 import com.ibm.ws.http.dispatcher.internal.channel.HttpDispatcherLink;
 import com.ibm.wsspi.genericbnf.HeaderField;
 import com.ibm.wsspi.http.channel.HttpRequestMessage;
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 public class LibertyRequest {
@@ -54,6 +56,19 @@ public String getHeaderValue(String name) {
     return hf != null ? hf.asString() : null;
   }
 
+  public List<String> getHeaderValues(String name) {
+    List<HeaderField> headers = httpRequestMessage.getHeaders(name);
+    if (headers.isEmpty()) {
+      return Collections.emptyList();
+    }
+    List<String> stringHeaders = new ArrayList<>(headers.size());
+    int i = 0;
+    for (HeaderField header : headers) {
+      stringHeaders.set(i++, header.asString());
+    }
+    return stringHeaders;
+  }
+
   public int peerPort() {
     return httpDispatcherLink.getRemotePort();
   }

instrumentation/liberty/liberty-dispatcher/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/liberty/dispatcher/LibertyResponse.java

@@ -5,16 +5,29 @@
 
 package io.opentelemetry.javaagent.instrumentation.liberty.dispatcher;
 
+import com.ibm.ws.http.dispatcher.internal.channel.HttpDispatcherLink;
+import com.ibm.wsspi.http.HttpResponse;
 import com.ibm.wsspi.http.channel.values.StatusCodes;
+import java.util.Collections;
+import java.util.List;
 
 public class LibertyResponse {
+  private final HttpDispatcherLink httpDispatcherLink;
   private final StatusCodes code;
 
-  public LibertyResponse(StatusCodes code) {
+  public LibertyResponse(HttpDispatcherLink httpDispatcherLink, StatusCodes code) {
+    this.httpDispatcherLink = httpDispatcherLink;
     this.code = code;
   }
 
   public int getStatus() {
     return code.getIntCode();
   }
+
+  public List<String> getHeaderValues(String name) {
+    HttpResponse response = httpDispatcherLink.getResponse();
+    // response is set to null on destroy(), so it shouldn't really ever be null in the middle of
+    // request processing, but just to be safe let's check it
+    return response == null ? Collections.emptyList() : response.getHeaders(name);
+  }
 }