NPE in HandlerFilterFunction of spring cloud gateway mvc

[bruce-jeong]

Describe the bug
hello.
First of all, the spring cloud gateway mvc version information I use is as follows.

• org.springframework.cloud:spring-cloud-gateway-server-mvc:4.1.4

The following exception occurs while calling HandlerFilterFunction, but it is difficult to determine the cause because the error occurs inside the FilterFunction. Could you please help resolve the issue?

java.util.concurrent.CompletionException: java.lang.NullPointerException: Cannot invoke "jdk.internal.net.http.Http1Exchange$Http1BodySubscriber.request(long)" because "this.bodySubscriber" is null
	at java.base/java.util.concurrent.CompletableFuture.encodeRelay(CompletableFuture.java:368)
	at java.base/java.util.concurrent.CompletableFuture.uniComposeStage(CompletableFuture.java:1189)
	at java.base/java.util.concurrent.CompletableFuture.thenCompose(CompletableFuture.java:2309)
	at java.net.http/jdk.internal.net.http.MultiExchange.responseAsyncImpl(MultiExchange.java:453)
	at java.net.http/jdk.internal.net.http.MultiExchange.lambda$responseAsync0$2(MultiExchange.java:341)
	at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1150)
	at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)
	at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1773)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.NullPointerException: Cannot invoke "jdk.internal.net.http.Http1Exchange$Http1BodySubscriber.request(long)" because "this.bodySubscriber" is null
	at java.net.http/jdk.internal.net.http.Http1Exchange.requestMoreBody(Http1Exchange.java:544)
	at java.net.http/jdk.internal.net.http.HttpClientImpl$DelegatingExecutor.execute(HttpClientImpl.java:157)
	at java.net.http/jdk.internal.net.http.Http1Exchange.getOutgoing(Http1Exchange.java:608)
	at java.net.http/jdk.internal.net.http.Http1Exchange$Http1Publisher$WriteTask.run(Http1Exchange.java:702)
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:205)
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:230)
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:303)
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:256)
	at java.net.http/jdk.internal.net.http.Http1Exchange.appendToOutgoing(Http1Exchange.java:532)
	at java.net.http/jdk.internal.net.http.Http1Exchange.appendToOutgoing(Http1Exchange.java:526)
	at java.net.http/jdk.internal.net.http.Http1Request$StreamSubscriber.onComplete(Http1Request.java:387)
	at org.springframework.http.client.OutputStreamPublisher$OutputStreamSubscription.invokeHandler(OutputStreamPublisher.java:338)
	... 1 more

Thanks in advance.

Sample
If possible, please provide a test case or sample application that reproduces
the problem. This makes it much easier for us to diagnose the problem and to verify that
we have fixed it.

[spencergibb]

I'm afraid without more information on how to replicate the issue, there's not much we can do.