pr review

Author: zeitlinger

instrumentation/spring/spring-webflux/spring-webflux-5.3/library/src/main/java/io/opentelemetry/instrumentation/spring/webflux/v5_3/internal/HeaderUtil.java

@@ -11,7 +11,6 @@
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
 import java.util.List;
-import java.util.Map;
 import org.springframework.http.HttpHeaders;
 
 /**
@@ -38,17 +37,13 @@ private static MethodHandle findGetHeadersMethod(MethodType methodType) {
   // 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"})
+  @SuppressWarnings("unchecked") // casting GET_HEADERS.invoke result
   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
+    if (headers != null) {
       try {
         return (List<String>) GET_HEADERS.invoke(headers, name, emptyList());
       } catch (Throwable t) {
-        // ignore
+        throw new IllegalStateException(t);
       }
     }
     return emptyList();