Apply attributes to the underlying HTTP request

See gh-29958

spring-web/src/testFixtures/java/org/springframework/web/testfixture/http/client/reactive/MockClientHttpRequest.java

@@ -121,6 +121,10 @@ public class MockClientHttpRequest extends AbstractClientHttpRequest implements
 				.forEach(cookie -> getHeaders().add(HttpHeaders.COOKIE, cookie.toString()));
 	}
 
+	@Override
+	protected void applyAttributes() {
+	}
+
 	@Override
 	public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
 		return doCommit(() -> Mono.defer(() -> this.writeHandler.apply(Flux.from(body))));