default void sendSignal(SignalRequest signalRequest, AuthData authData, Monitor monitor)
    throws CopyExceptionWithFailureReason, IOException, RetryException {
    monitor.info(() -> "Default Signaller::" + signalRequest.toString());
  }
Sends the signal to thw provider typically over the Network. The default implementation logs the
signal info via {@link Monitor}. By default, the signal is turned ON via "transferSignalEnabled"
settings flag. Signalling can be explicitly turned off by setting "transferSignalEnabled" to
false in the Settings.

@see YamlSettingsExtension - for turning off the Signalling feature.
@see JobProcessor - where the signals are triggered.
@see WorkerModule - feature flag (transferSignalEnabled) is wired.
portability-spi-transfer/src/main/java/org/datatransferproject/spi/transfer/provider/SignalHandler.java