FULL PRODUCT VERSION :
java version "10" 2018-03-20
Java(TM) SE Runtime Environment 18.3 (build 10+46)
Java HotSpot(TM) 64-Bit Server VM 18.3 (build 10+46, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 10.0.16299.334]

EXTRA RELEVANT SYSTEM CONFIGURATION :
java.lang.IllegalArgumentException

A DESCRIPTION OF THE PROBLEM :
Some UTF-8 characters like "š" can't be used with HttpClient. However others like "å" can be.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the source code


ERROR MESSAGES/STACK TRACES THAT OCCUR :
WARNING: Using incubator modules: jdk.incubator.httpclient
Exception in thread "main" java.lang.IllegalArgumentException: char=353
at jdk.incubator.httpclient/jdk.incubator.http.internal.hpack.Huffman.codeOf(Huffman.java:559)
at jdk.incubator.httpclient/jdk.incubator.http.internal.hpack.Huffman.lengthOf(Huffman.java:524)
at jdk.incubator.httpclient/jdk.incubator.http.internal.hpack.StringWriter.configure(StringWriter.java:79)
at jdk.incubator.httpclient/jdk.incubator.http.internal.hpack.StringWriter.configure(StringWriter.java:62)
at jdk.incubator.httpclient/jdk.incubator.http.internal.hpack.IndexNameValueWriter.value(IndexNameValueWriter.java:64)
at jdk.incubator.httpclient/jdk.incubator.http.internal.hpack.Encoder.literal(Encoder.java:422)
at jdk.incubator.httpclient/jdk.incubator.http.internal.hpack.Encoder.header(Encoder.java:245)
at jdk.incubator.httpclient/jdk.incubator.http.internal.hpack.Encoder.header(Encoder.java:198)
at jdk.incubator.httpclient/jdk.incubator.http.Http2Connection.encodeHeadersImpl(Http2Connection.java:927)
at jdk.incubator.httpclient/jdk.incubator.http.Http2Connection.encodeHeaders(Http2Connection.java:878)
at jdk.incubator.httpclient/jdk.incubator.http.Http2Connection.encodeHeaders(Http2Connection.java:951)
at jdk.incubator.httpclient/jdk.incubator.http.Http2Connection.sendFrame(Http2Connection.java:984)
at jdk.incubator.httpclient/jdk.incubator.http.Stream.sendHeadersAsync(Stream.java:547)
at jdk.incubator.httpclient/jdk.incubator.http.Exchange.lambda$responseAsyncImpl0$8(Exchange.java:322)
at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1072)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2073)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SSLFlowDelegate.setALPN(SSLFlowDelegate.java:164)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SSLFlowDelegate.access$200(SSLFlowDelegate.java:81)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SSLFlowDelegate$Reader.processData(SSLFlowDelegate.java:340)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SSLFlowDelegate$Reader$ReaderDownstreamPusher.run(SSLFlowDelegate.java:215)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler$SynchronizedRestartableTask.run(SequentialScheduler.java:175)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:147)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler$TryEndDeferredCompleter.complete(SequentialScheduler.java:315)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:198)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:271)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:224)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SSLFlowDelegate$Reader.incoming(SSLFlowDelegate.java:242)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SubscriberWrapper.incomingCaller(SubscriberWrapper.java:388)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SubscriberWrapper.onNext(SubscriberWrapper.java:343)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SubscriberWrapper.onNext(SubscriberWrapper.java:58)
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$InternalReadPublisher$InternalReadSubscription.read(SocketTube.java:739)
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$SocketFlowTask.run(SocketTube.java:171)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:198)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:271)
at jdk.incubator.httpclient/jdk.incubator.http.internal.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:224)
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$InternalReadPublisher$InternalReadSubscription.signalReadable(SocketTube.java:675)
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$InternalReadPublisher$ReadEvent.signalEvent(SocketTube.java:829)
at jdk.incubator.httpclient/jdk.incubator.http.SocketTube$SocketFlowEvent.handle(SocketTube.java:243)
at jdk.incubator.httpclient/jdk.incubator.http.HttpClientImpl$SelectorManager.handleEvent(HttpClientImpl.java:769)
at jdk.incubator.httpclient/jdk.incubator.http.HttpClientImpl$SelectorManager.run(HttpClientImpl.java:731)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package Main;

import jdk.incubator.http.HttpClient;
import jdk.incubator.http.HttpRequest;
import jdk.incubator.http.HttpResponse;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

public class Main {
    public static void main(String[] args) {
        try {
            HttpRequest r = HttpRequest.newBuilder().uri(new URI("https://lolnames.gg/en/euw/šaba/")).build();
            HttpClient.newHttpClient().send(r, HttpResponse.BodyHandler.asString());
        } catch (URISyntaxException | IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}




-------- module-info.java ---------



module Java10Bug {
    requires jdk.incubator.httpclient;
}
---------- END SOURCE ----------