* sure that these (potentially overridden) methods are invoked only once, and instance created by those methods are
 * memorized and kept as long as supplier instance is kept open.
 * <p>
 * This class is not thread safe and must be used from one thread only, while the constructed {@link RepositorySystem}
 * is thread safe.
 * <p>

        if (testTransferListener != null) {
            testTransferListener.addTransfer(resourceName);
        }
    }

    public boolean getIfNewer(String resourceName, File destination, long timestamp)
            throws TransferFailedException, ResourceDoesNotExistException, AuthorizationException {
        if (!insideGet) {
            addTransfer("getIfNewer " + resourceName);
        }