presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/storage/FileStorageService.java/FileStorageService/start
class FileStorageService:    @Override
    @PostConstruct
    public void start()
    {
        deleteStagingFilesAsync();
        createParents(new File(baseStagingDir, "."));
        createParents(new File(baseStorageDir, "."));
        createParents(new File(baseQuarantineDir, "."));
    }