open-telemetry · trask · Nov 15, 2025 · Nov 15, 2025
@@ -3,14 +3,15 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-package io.opentelemetry.instrumentation.spring.webflux.v5_3;
+package io.opentelemetry.instrumentation.spring.web.v3_1;
 
 import static java.util.Collections.emptyList;
 
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
 import java.util.List;
+import java.util.Map;
 import javax.annotation.Nullable;
 import org.springframework.http.HttpHeaders;
 
@@ -19,14 +20,7 @@ class HeaderUtil {
 
   static {
     // since spring web 7.0
-    MethodHandle methodHandle =
-        findGetHeadersMethod(MethodType.methodType(List.class, String.class, List.class));
-    if (methodHandle == null) {
-      // up to spring web 7.0
-      methodHandle =
-          findGetHeadersMethod(MethodType.methodType(Object.class, Object.class, Object.class));
-    }
-    GET_HEADERS = methodHandle;
+    GET_HEADERS = findGetHeadersMethod(MethodType.methodType(List.class, String.class, List.class));
   }
 
   private static MethodHandle findGetHeadersMethod(MethodType methodType) {
@@ -37,9 +31,16 @@ private static MethodHandle findGetHeadersMethod(MethodType methodType) {
     }
   }
 
-  @SuppressWarnings("unchecked") // casting MethodHandle.invoke result
+  // before spring web 7.0 HttpHeaders implements Map<String, List<String>>, this triggers
+  // errorprone BadInstanceof warning since errorpone is not aware that this instanceof check does
+  // not pass with spring web 7.0+
+  @SuppressWarnings({"unchecked", "BadInstanceof"})
   static List<String> getHeader(HttpHeaders headers, String name) {
-    if (GET_HEADERS != null) {
+    if (headers instanceof Map) {
+      // before spring web 7.0
+      return ((Map<String, List<String>>) headers).getOrDefault(name, emptyList());
+    } else if (GET_HEADERS != null) {
+      // spring web 7.0
       try {
         return (List<String>) GET_HEADERS.invoke(headers, name, emptyList());
       } catch (Throwable t) {

@@ -5,15 +5,12 @@
 
 package io.opentelemetry.instrumentation.spring.web.v3_1;
 
-import static java.util.Collections.emptyList;
-
 import io.opentelemetry.instrumentation.api.semconv.http.HttpClientAttributesGetter;
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
 import java.util.List;
 import javax.annotation.Nullable;
-import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpRequest;
 import org.springframework.http.client.ClientHttpResponse;
 
@@ -23,7 +20,6 @@ enum SpringWebHttpAttributesGetter
 
   @Nullable private static final MethodHandle GET_STATUS_CODE;
   @Nullable private static final MethodHandle STATUS_CODE_VALUE;
-  @Nullable private static final MethodHandle GET_HEADERS;
 
   static {
     MethodHandles.Lookup lookup = MethodHandles.publicLookup();
@@ -58,24 +54,6 @@ enum SpringWebHttpAttributesGetter
 
     GET_STATUS_CODE = getStatusCode;
     STATUS_CODE_VALUE = statusCodeValue;
-
-    // since spring web 7.0
-    MethodHandle methodHandle =
-        findGetHeadersMethod(MethodType.methodType(List.class, String.class, List.class));
-    if (methodHandle == null) {
-      // up to spring web 7.0
-      methodHandle =
-          findGetHeadersMethod(MethodType.methodType(Object.class, Object.class, Object.class));
-    }
-    GET_HEADERS = methodHandle;
-  }
-
-  private static MethodHandle findGetHeadersMethod(MethodType methodType) {
-    try {
-      return MethodHandles.lookup().findVirtual(HttpHeaders.class, "getOrDefault", methodType);
-    } catch (Throwable t) {
-      return null;
-    }
   }
 
   @Override
@@ -91,19 +69,7 @@ public String getUrlFull(HttpRequest httpRequest) {
 
   @Override
   public List<String> getHttpRequestHeader(HttpRequest httpRequest, String name) {
-    return getHeader(httpRequest.getHeaders(), name);
-  }
-
-  @SuppressWarnings("unchecked") // casting MethodHandle.invoke result
-  private static List<String> getHeader(HttpHeaders headers, String name) {
-    if (GET_HEADERS != null) {
-      try {
-        return (List<String>) GET_HEADERS.invoke(headers, name, emptyList());
-      } catch (Throwable t) {
-        // ignore
-      }
-    }
-    return emptyList();
+    return HeaderUtil.getHeader(httpRequest.getHeaders(), name);
   }
 
   @Override
@@ -125,7 +91,7 @@ public Integer getHttpResponseStatusCode(
   @Override
   public List<String> getHttpResponseHeader(
       HttpRequest httpRequest, ClientHttpResponse clientHttpResponse, String name) {
-    return getHeader(clientHttpResponse.getHeaders(), name);
+    return HeaderUtil.getHeader(clientHttpResponse.getHeaders(), name);
   }
 
   @Override

@@ -6,6 +6,7 @@
 package io.opentelemetry.instrumentation.spring.webflux.v5_3;
 
 import io.opentelemetry.instrumentation.api.semconv.http.HttpServerAttributesGetter;
+import io.opentelemetry.instrumentation.spring.webflux.v5_3.internal.HeaderUtil;
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;

@@ -8,6 +8,7 @@
 import static java.util.Collections.emptyIterator;
 
 import io.opentelemetry.context.propagation.TextMapGetter;
+import io.opentelemetry.instrumentation.spring.webflux.v5_3.internal.HeaderUtil;
 import java.util.Iterator;
 import javax.annotation.Nullable;
 import org.springframework.web.server.ServerWebExchange;

@@ -0,0 +1,59 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.spring.webflux.v5_3.internal;
+
+import static java.util.Collections.emptyList;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.util.List;
+import java.util.Map;
+import javax.annotation.Nullable;
+import org.springframework.http.HttpHeaders;
+
+/**
+ * This class is internal and experimental. Its APIs are unstable and can change at any time. Its
+ * APIs (or a version of them) may be promoted to the public stable API in the future, but no
+ * guarantees are made.
+ */
+public final class HeaderUtil {
+  @Nullable private static final MethodHandle GET_HEADERS;
+
+  static {
+    // since spring web 7.0
+    GET_HEADERS = findGetHeadersMethod(MethodType.methodType(List.class, String.class, List.class));
+  }
+
+  private static MethodHandle findGetHeadersMethod(MethodType methodType) {
+    try {
+      return MethodHandles.lookup().findVirtual(HttpHeaders.class, "getOrDefault", methodType);
+    } catch (Throwable t) {
+      return null;
+    }
+  }
+
+  // before spring web 7.0 HttpHeaders implements Map<String, List<String>>, this triggers
+  // errorprone BadInstanceof warning since errorpone is not aware that this instanceof check does
+  // not pass with spring web 7.0+
+  @SuppressWarnings({"unchecked", "BadInstanceof"})
+  public static List<String> getHeader(HttpHeaders headers, String name) {
+    if (headers instanceof Map) {
+      // before spring web 7.0
+      return ((Map<String, List<String>>) headers).getOrDefault(name, emptyList());
+    } else if (GET_HEADERS != null) {
+      // spring web 7.0
+      try {
+        return (List<String>) GET_HEADERS.invoke(headers, name, emptyList());
+      } catch (Throwable t) {
+        // ignore
+      }
+    }
+    return emptyList();
+  }
+
+  private HeaderUtil() {}
+}
@@ -5,15 +5,9 @@
 
 package io.opentelemetry.instrumentation.spring.webflux.v5_3.internal;
 
-import static java.util.Collections.emptyList;
-
 import io.opentelemetry.instrumentation.api.semconv.http.HttpClientAttributesGetter;
-import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
-import java.lang.invoke.MethodType;
 import java.util.List;
 import javax.annotation.Nullable;
-import org.springframework.http.HttpHeaders;
 import org.springframework.web.reactive.function.client.ClientRequest;
 import org.springframework.web.reactive.function.client.ClientResponse;
 
@@ -25,28 +19,6 @@ public enum WebClientHttpAttributesGetter
     implements HttpClientAttributesGetter<ClientRequest, ClientResponse> {
   INSTANCE;
 
-  private static final MethodHandle GET_HEADERS;
-
-  static {
-    // since webflux 7.0
-    MethodHandle methodHandle =
-        findGetHeadersMethod(MethodType.methodType(List.class, String.class, List.class));
-    if (methodHandle == null) {
-      // up to webflux 7.0
-      methodHandle =
-          findGetHeadersMethod(MethodType.methodType(Object.class, Object.class, Object.class));
-    }
-    GET_HEADERS = methodHandle;
-  }
-
-  private static MethodHandle findGetHeadersMethod(MethodType methodType) {
-    try {
-      return MethodHandles.lookup().findVirtual(HttpHeaders.class, "getOrDefault", methodType);
-    } catch (Throwable t) {
-      return null;
-    }
-  }
-
   @Override
   public String getUrlFull(ClientRequest request) {
     return request.url().toString();
@@ -58,16 +30,8 @@ public String getHttpRequestMethod(ClientRequest request) {
   }
 
   @Override
-  @SuppressWarnings("unchecked") // casting MethodHandle.invoke result
   public List<String> getHttpRequestHeader(ClientRequest request, String name) {
-    if (GET_HEADERS != null) {
-      try {
-        return (List<String>) GET_HEADERS.invoke(request.headers(), name, emptyList());
-      } catch (Throwable t) {
-        // ignore
-      }
-    }
-    return emptyList();
+    return HeaderUtil.getHeader(request.headers(), name);
   }
 
   @Override