WebSocket Message InputStream read() returns signed byte

[jspechts]

Jetty version(s)

10.0.12

Java version/vendor (use: java -version)

openjdk version "11.0.10" 2021-01-19 LTS
OpenJDK Runtime Environment Zulu11.45+28-SA (build 11.0.10+9-LTS)
OpenJDK 64-Bit Server VM Zulu11.45+28-SA (build 11.0.10+9-LTS, mixed mode)

OS type/version

Tested on macOS 12.6.1 (though this is likely a OS-agnostic issue)

Description

In Jetty 9, reading any unsigned byte from 0 to 255 inclusive using the InputStream#read() API against the InputStream instance injected by Jetty into the method annotated with @OnWebSocketMessage for class annotated with @WebSocket worked well.

However, in Jetty 10, attempting to read an unsigned byte in the range 128 to 255 inclusive using the same setup fails since values in this range are returned as signed bytes (-128 to -1, inclusive), which breaks the InputStream#read() contract.

This is causing a problem for us when we use DataOutputStream / DataInputStream to write / read shorts (for example) using Jetty's WebSocket OutputStream / InputStream, since the signed byte returned by Jetty is interpreted as EOF.

How to reproduce?

See: https://github.com/jspechts/IGN-6520-JETTY-SSCCE