* making it not very suitable for usage in collections.
 */
record TransferResourceIdentifier(String repositoryId, String repositoryUrl, String resourceName, @Nullable File file) {
    TransferResourceIdentifier(TransferResource resource) {
        this(resource.getRepositoryId(), resource.getRepositoryUrl(), resource.getResourceName(), resource.getFile());
    }

            throw new RuntimeException(e);
        }
    }

    private final ConcurrentHashMap<TransferResourceIdentifier, Boolean> ongoing = new ConcurrentHashMap<>();

    @Override
    public void transferInitiated(TransferEvent event) {
        ongoing.putIfAbsent(new TransferResourceIdentifier(event.getResource()), Boolean.TRUE);
        put(event, false);
    }

    @Override

    public void transferSucceeded(TransferEvent event) {
        transfers.remove(new TransferResourceIdentifier(event.getResource()));
        overridePreviousTransfer(event);

        super.transferSucceeded(event);
    }

    @Override
    public void transferFailed(TransferEvent event) {
        transfers.remove(new TransferResourceIdentifier(event.getResource()));
        overridePreviousTransfer(event);