$ java src/Fallback.java https://localhost:4433/hello 120     (server: h2 + h1.1 on TCP only; nothing listens on UDP 4433)
request HTTP_3 (ANY)       -> HTTP_2                                                                 after  3340 ms
client HTTP_3 (ANY)        -> HTTP_2                                                                 after    31 ms
request HTTP_3_URI_ONLY    -> java.net.ConnectException: No response from peer for 30 seconds        after 60016 ms

$ java -Djdk.httpclient.http3.maxDirectConnectionTimeout=1 src/Fallback.java https://localhost:4433/hello 120     (same server)
request HTTP_3 (ANY)       -> HTTP_2                                                                 after   501 ms
client HTTP_3 (ANY)        -> HTTP_2                                                                 after    45 ms
request HTTP_3_URI_ONLY    -> java.net.ConnectException: No response from peer for 30 seconds        after 60016 ms

$ java -Djdk.httpclient.quic.maxInitialTimeout=3 src/Fallback.java https://localhost:4433/hello 120     (same server)
request HTTP_3 (ANY)       -> HTTP_2                                                                 after  3338 ms
client HTTP_3 (ANY)        -> HTTP_2                                                                 after    39 ms
request HTTP_3_URI_ONLY    -> java.net.ConnectException: No response from peer for 3 seconds         after  6011 ms

$ java src/Discovery.java https://localhost:4433/hello     (server: HTTP/1.1 only, TCP)
ANY              -> HTTP_1_1 HTTP_1_1 HTTP_1_1 HTTP_1_1
ALT_SVC          -> HTTP_1_1 HTTP_1_1 HTTP_1_1 HTTP_1_1
HTTP_3_URI_ONLY  -> ConnectException(No response from peer for 30 seconds) ConnectException(No response from peer for 30 seconds) ConnectException(No response from peer for 30 seconds) ConnectException(No response from peer for 30 seconds)