// We're (ab)using CacheLoader -- this is NOT the cache. We're merely using it to schedule concurrent image generation jobs.
.build(new CacheLoader<ImageGenerationJob<P>, Property>() {

    @Override
    public Property load(ImageGenerationJob<P> job) throws Exception {
        try {
            return generateAndStore(job.getGenerator(), job.getParams());
        } catch (IOException | ImagingException e) {
            // the LoadingCache will further wrap these in ExecutionExceptions, and we will, in turn, unwrap them ...
            throw new RuntimeException(e);
        }
    }
});

} catch (ExecutionException e) {
    // thrown if the LoadingCache's Function failed
    unwrapRuntimeException(e);
}