Fix spring web latest dep test (#15301)

Author: laurit

instrumentation/spring/spring-web/spring-web-3.1/library/src/main/java/io/opentelemetry/instrumentation/spring/web/v3_1/SpringWebHttpAttributesGetter.java

@@ -13,40 +13,25 @@
 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;
 
 enum SpringWebHttpAttributesGetter
     implements HttpClientAttributesGetter<HttpRequest, ClientHttpResponse> {
   INSTANCE;
 
-  @Override
-  public String getHttpRequestMethod(HttpRequest httpRequest) {
-    return httpRequest.getMethod().name();
-  }
-
-  @Override
-  @Nullable
-  public String getUrlFull(HttpRequest httpRequest) {
-    return httpRequest.getURI().toString();
-  }
-
-  @Override
-  public List<String> getHttpRequestHeader(HttpRequest httpRequest, String name) {
-    return httpRequest.getHeaders().getOrDefault(name, emptyList());
-  }
-
   @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();
+
     MethodHandle getStatusCode = null;
     MethodHandle statusCodeValue = null;
     Class<?> httpStatusCodeClass = null;
 
-    MethodHandles.Lookup lookup = MethodHandles.publicLookup();
-
     try {
       httpStatusCodeClass = Class.forName("org.springframework.http.HttpStatusCode");
     } catch (ClassNotFoundException e) {
@@ -73,6 +58,52 @@ public List<String> getHttpRequestHeader(HttpRequest httpRequest, String name) {
 
     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
+  public String getHttpRequestMethod(HttpRequest httpRequest) {
+    return httpRequest.getMethod().name();
+  }
+
+  @Override
+  @Nullable
+  public String getUrlFull(HttpRequest httpRequest) {
+    return httpRequest.getURI().toString();
+  }
+
+  @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();
   }
 
   @Override
@@ -94,7 +125,7 @@ public Integer getHttpResponseStatusCode(
   @Override
   public List<String> getHttpResponseHeader(
       HttpRequest httpRequest, ClientHttpResponse clientHttpResponse, String name) {
-    return clientHttpResponse.getHeaders().getOrDefault(name, emptyList());
+    return getHeader(clientHttpResponse.getHeaders(), name);
   }
 
   @Override