return null;
        }).filter(f -> f != null).forEach(f -> {
            try {
                f.get();
            } catch (final Exception e) {
                logger.warn("Failed to process a thumbnail generation.", e);
            }
        });

        if (!idList.isEmpty()) {
            thumbnailQueueBhv.queryDelete(cb -> {
                cb.query().setId_InScope(idList);
            });