MicrosCounter
A deterministic microsecond source for tests. Each call returns the previous value plus one. It is not a wall clock and it is not a monotonic clock.
Do not use this in production. UtpStream stamps every outgoing packet with this value. The peer subtracts that stamp from its own clock and echoes the difference back. UtpStream feeds the echoed difference into its queuing-delay estimate. LEDBAT then scales the congestion window by the distance between that estimate and UtpStream.TARGET_DELAY_MICROS. A counter makes the estimate meaningless, so the window stops tracking real congestion.
Production streams must inject MonotonicMicros.