minor fix and update to work on latest 2.1.0.BUILD-SNAPSHOT to use core check in CFUtils

spring-web-reactive/src/main/java/org/springframework/reactive/util/CompletableFutureUtils.java

@@ -24,6 +24,8 @@ import org.reactivestreams.Publisher;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 import reactor.core.error.Exceptions;
+import reactor.core.error.SpecificationExceptions;
+import reactor.core.support.BackpressureUtils;
 import reactor.rx.Stream;
 import reactor.rx.action.Action;
 import reactor.rx.subscription.ReactiveSubscription;
@@ -111,15 +113,19 @@ public class CompletableFutureUtils {
 
 					@Override
 					public void request(long elements) {
-						Action.checkRequest(elements);
+						try{
+							BackpressureUtils.checkRequest(elements);
+						}catch(SpecificationExceptions.Spec309_NullOrNegativeRequest iae){
+							subscriber.onError(iae);
+							return;
+						}
 						if (isComplete()) return;
 
 						try {
 							future.whenComplete((result, error) -> {
 								if (error != null) {
 									onError(error);
-								}
+								} else {
-								else {
 									subscriber.onNext(result);
 									onComplete();
 								}