also, it feels like, since the only events the RollupEventEmitter actually performs are rollup events, the `rollupEventName` should exist inside of the `RollupEventEmitter` and the method should be

```foo.java
emit(RollupEvent... rollupEvents) {
  super.emit(ROLLUP_EVENT_NAME, rollupEvents);
}
```


another nit: constants are typically all-caps, static, and interned. i.e: `private final static String ROLLUP_EVENT_NAME = "rollup".intern();`