presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/backup/BackupConfig.java/BackupConfig/setBackupThreads
class BackupConfig:    @Config("backup.threads")
    @ConfigDescription("Maximum number of shards to backup at once")
    public BackupConfig setBackupThreads(int backupThreads)
    {
        this.backupThreads = backupThreads;
        return this;
    }