From fea157fc70f5f5c7511154fdd060243ec5363e4f Mon Sep 17 00:00:00 2001
From: Lauri Tulmin <ltulmin@splunk.com>
Date: Thu, 11 Aug 2022 19:24:48 +0300
Subject: [PATCH] Grizzly: capture all matching request & response headers
 (#6463)

---
 .../grizzly/GrizzlyHttpAttributesGetter.java    | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/instrumentation/grizzly-2.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/grizzly/GrizzlyHttpAttributesGetter.java b/instrumentation/grizzly-2.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/grizzly/GrizzlyHttpAttributesGetter.java
index 8ce16215416d..320820dde4c6 100644
--- a/instrumentation/grizzly-2.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/grizzly/GrizzlyHttpAttributesGetter.java
+++ b/instrumentation/grizzly-2.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/grizzly/GrizzlyHttpAttributesGetter.java
@@ -6,9 +6,9 @@
 package io.opentelemetry.javaagent.instrumentation.grizzly;
 
 import static java.util.Collections.emptyList;
-import static java.util.Collections.singletonList;
 
 import io.opentelemetry.instrumentation.api.instrumenter.http.HttpServerAttributesGetter;
+import java.util.ArrayList;
 import java.util.List;
 import javax.annotation.Nullable;
 import org.glassfish.grizzly.http.HttpRequestPacket;
@@ -24,8 +24,16 @@ public String method(HttpRequestPacket request) {
 
   @Override
   public List<String> requestHeader(HttpRequestPacket request, String name) {
-    String value = request.getHeader(name);
-    return value == null ? emptyList() : singletonList(value);
+    return toHeaderList(request.getHeaders().values(name));
+  }
+
+  private static List<String> toHeaderList(Iterable<String> values) {
+    if (values.iterator().hasNext()) {
+      List<String> result = new ArrayList<>();
+      values.forEach(result::add);
+      return result;
+    }
+    return emptyList();
   }
 
   @Override
@@ -36,8 +44,7 @@ public Integer statusCode(HttpRequestPacket request, HttpResponsePacket response
   @Override
   public List<String> responseHeader(
       HttpRequestPacket request, HttpResponsePacket response, String name) {
-    String value = response.getHeader(name);
-    return value == null ? emptyList() : singletonList(value);
+    return toHeaderList(response.getHeaders().values(name));
   }
 
   @Override