public WalletAppKit setCheckpoints(InputStream checkpoints) {
        if (this.checkpoints != null)
            Closeables.closeQuietly(checkpoints);
        this.checkpoints = checkNotNull(checkpoints);
        return this;
    }
public WalletAppKit setCheckpoints ( InputStream checkpoints ) { if ( this . checkpoints != null ) Closeables . closeQuietly ( checkpoints ) ; this . checkpoints = checkNotNull ( checkpoints ) ; return this ; }
If set, the file is expected to contain a checkpoints file calculated with BuildCheckpoints. It makes initial
block sync faster for new users - please refer to the documentation on the bitcoinj website
(https://bitcoinj.github.io/speeding-up-chain-sync) for further details.