presto-redis/src/main/java/io/prestosql/plugin/redis/RedisTableDescriptionSupplier.java/RedisTableDescriptionSupplier/listFiles
class RedisTableDescriptionSupplier:    private static List<File> listFiles(File dir)
    {
        if ((dir != null) && dir.isDirectory()) {
            File[] files = dir.listFiles();
            if (files != null) {
                log.debug("Considering files: %s", asList(files));
                return ImmutableList.copyOf(files);
            }
        }
        return ImmutableList.of();
    }