HTTP/2 HEAD responses include a body.

If HTTP/2 is enabled in the Undertow server and the client also supports HTTP/2, and the client makes a HEAD request, the response from the server will include a body. As I understand it, HEAD responses should not include a body. https://tools.ietf.org/html/rfc7231#section-4.3.2

If HTTP/2 is not enabled on the server or the client does not support HTTP/2, then the responses to HEAD do not include bodies, which is the desired behavior.

I notice in HttpServerConnection.getSinkConduit, it calls HttpTransferEncoding.createSinkConduit, and that second method has code related to HEAD requests:

https://github.com/undertow-io/undertow/blob/f29cd1f3a16bfe6bfbc5a8d4cb2052ececc2063e/core/src/main/java/io/undertow/server/protocol/http/HttpServerConnection.java#L202-L210

https://github.com/undertow-io/undertow/blob/f29cd1f3a16bfe6bfbc5a8d4cb2052ececc2063e/core/src/main/java/io/undertow/server/protocol/http/HttpTransferEncoding.java#L202-L250

Meanwhile in Http2ServerConnection.getSinkConduit, there seems to be no HEAD-related code:

https://github.com/undertow-io/undertow/blob/f29cd1f3a16bfe6bfbc5a8d4cb2052ececc2063e/core/src/main/java/io/undertow/server/protocol/http2/Http2ServerConnection.java#L325-L332

Maybe that is the issue? That the code in Undertow that ensures HEAD responses are empty is in the HTTP 1.x code path but missing from the HTTP/2 code path?