removes unneeded cast to GatewayServerResponse for header manipulation.

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/AfterFilterFunctions.java

@@ -30,20 +30,16 @@ public interface AfterFilterFunctions {
 
 	static BiFunction<ServerRequest, ServerResponse, ServerResponse> addResponseHeader(String name, String... values) {
 		return (request, response) -> {
-			if (response instanceof GatewayServerResponse res) {
-				String[] expandedValues = MvcUtils.expandMultiple(request, values);
-				res.headers().addAll(name, Arrays.asList(expandedValues));
-			}
+			String[] expandedValues = MvcUtils.expandMultiple(request, values);
+			response.headers().addAll(name, Arrays.asList(expandedValues));
 			return response;
 		};
 	}
 
 	static BiFunction<ServerRequest, ServerResponse, ServerResponse> setResponseHeader(String name, String value) {
 		return (request, response) -> {
-			if (response instanceof GatewayServerResponse res) {
-				String expandedValue = MvcUtils.expand(request, value);
-				res.headers().set(name, expandedValue);
-			}
+			String expandedValue = MvcUtils.expand(request, value);
+			response.headers().set(name, expandedValue);
 			return response;
 		};
 	}

spring-cloud-gateway-server-mvc/src/test/java/org/springframework/cloud/gateway/server/mvc/ServerMvcIntegrationTests.java

@@ -418,8 +418,8 @@ public class ServerMvcIntegrationTests {
 
 	@Test
 	public void removeRequestParameterWorks() {
-		restClient.get().uri("/anything/removerequestparameter?foo=bar").header("test", "removerequestparam").exchange().expectStatus()
-				.isOk().expectBody(Map.class).consumeWith(res -> {
+		restClient.get().uri("/anything/removerequestparameter?foo=bar").header("test", "removerequestparam").exchange()
+				.expectStatus().isOk().expectBody(Map.class).consumeWith(res -> {
 					Map<String, Object> map = res.getResponseBody();
 					Map<String, Object> args = getMap(map, "args");
 					assertThat(args).doesNotContainKey("foo");
@@ -733,6 +733,7 @@ public class ServerMvcIntegrationTests {
 					.build();
 			// @formatter:on
 		}
+
 	}
 
 	@RestController