NullPointerException when webhook callback returns a 204

2017-09-29 09:31:17,043 WARN  [ForkJoinPool.commonPool-worker-12]  c.a.w.i.p.DefaultWebhookDispatcher Webhook callback failed
java.lang.NullPointerException: null
        at org.apache.commons.io.input.BoundedInputStream.read(BoundedInputStream.java:123)
        at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
        at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
        at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
        at java.io.InputStreamReader.read(InputStreamReader.java:184)
        at java.io.BufferedReader.fill(BufferedReader.java:161)
        at java.io.BufferedReader.read1(BufferedReader.java:212)
        at java.io.BufferedReader.read(BufferedReader.java:286)
        at java.io.Reader.read(Reader.java:100)
        at com.google.common.io.CharStreams.copy(CharStreams.java:68)
        at com.google.common.io.CharStreams.toStringBuilder(CharStreams.java:99)
        at com.google.common.io.CharStreams.toString(CharStreams.java:86)
        at com.atlassian.bitbucket.internal.webhook.history.SimpleDetailedResponse.loadBody(SimpleDetailedResponse.java:104)
        at com.atlassian.bitbucket.internal.webhook.history.SimpleDetailedResponse.<init>(SimpleDetailedResponse.java:38)
        at com.atlassian.bitbucket.internal.webhook.history.SimpleDetailedInvocation.<init>(SimpleDetailedInvocation.java:30)
        at com.atlassian.bitbucket.internal.webhook.history.DefaultInvocationHistoryService.logInvocationSuccess(DefaultInvocationHistoryService.java:138)
        at com.atlassian.bitbucket.internal.webhook.history.WebhookInvocationHistorian.onSuccess(WebhookInvocationHistorian.java:80)
        at com.atlassian.webhooks.internal.publish.DefaultWebhookDispatcher.lambda$onSuccess$5(DefaultWebhookDispatcher.java:222)
        at com.atlassian.webhooks.internal.publish.DefaultWebhookDispatcher.lambda$safely$1(DefaultWebhookDispatcher.java:143)
        at java.lang.Iterable.forEach(Iterable.java:75)
        at com.atlassian.webhooks.internal.publish.DefaultWebhookDispatcher.onSuccess(DefaultWebhookDispatcher.java:217)
        at com.atlassian.webhooks.internal.publish.DefaultWebhookDispatcher.lambda$dispatch$0(DefaultWebhookDispatcher.java:99)
        at java.util.concurrent.CompletableFuture.uniHandle(CompletableFuture.java:822)
        at java.util.concurrent.CompletableFuture$UniHandle.tryFire(CompletableFuture.java:797)
        at java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:443)
        at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
        at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
        at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
        at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)