The application-layer can also do blocking reads. If the application asks to read and there's nothing available, we need to hold that thread until either the bytes arrive, the stream is closed, or a timeout elapses. If we get bytes but there's nobody asking for them, we buffer them. We don't consider bytes as delivered for flow control until they're consumed by the application.

        ) {
          taskRunner.assertThreadHoldsLock()
          check(waitingCoordinatorTask == null)
          if (nanos == 0L) return

          // Yield until notified, interrupted, or the duration elapses.
          val waitUntil = nanoTime + nanos
          val self = currentTask
          waitingCoordinatorTask = self
          waitingCoordinatorNotified = false
          waitingCoordinatorInterrupted = false

2018..2023    ; valid                  ;      ; NV8    # 1.1  LEFT SINGLE QUOTATION MARK..TRIANGULAR BULLET
2024..2026    ; disallowed                             # 1.1  ONE DOT LEADER..HORIZONTAL ELLIPSIS
2027          ; valid                  ;      ; NV8    # 1.1  HYPHENATION POINT
2028..202E    ; disallowed                             # 1.1  LINE SEPARATOR..RIGHT-TO-LEFT OVERRIDE