/**
     * Maps the given progress event. Returns {@code null} of the event should be discarded and not forwarded to the client.
     */
    @Nullable
    default InternalProgressEvent createProgressEvent(TO descriptor, OperationProgressEvent progressEvent) {
        return null;
    }

        return new DefaultOperationStartedProgressEvent(startEvent.getStartTime(), descriptor);
    }

    @Nullable
    @Override
    public InternalProgressEvent createProgressEvent(DefaultFileDownloadDescriptor descriptor, OperationProgressEvent progressEvent) {
        if (progressEvent.getDetails() instanceof OperationProgressDetails) {

        }

        @Override
        public void progress(OperationProgressEvent progressEvent) {
            InternalProgressEvent mapped = mapper.createProgressEvent(descriptor, progressEvent);
            if (mapped != null) {
                progressEventConsumer.progress(mapped);
            }
        }

        @Override

        1 * consumer.started(clientStartEvent)
        0 * _

        when:
        generator.progress(operationId, progressEvent)

        then:
        1 * mapper2.createProgressEvent(clientDescriptor, progressEvent) >> mappedProgressEvent
        1 * consumer.progress(mappedProgressEvent)
        0 * _

        when:
        generator.finished(operation, finishEvent)

        then: