/**
* Builder for a spec based rolling sink. (most general version, does not
* necessarily output to files!).
*/
public static SinkBuilder builder() {
return new SinkBuilder() {
@Override
public EventSink build(Context ctx, String... argv) {
Preconditions.checkArgument(argv.length >= 2 && argv.length <= 3,
"roll(rollmillis[, checkmillis]) { sink }");
String spec = argv[0];