public void removeAllFanOuts() {
    Set<String> fanOutKeys = fanOutStore.all().keySet();
    for (String key : fanOutKeys) {
      fanOutStore.delete(key);
    }
    fanOutStore.flush();
  }
Deletes all fanned out {@link Startpoint}s
samza-core/src/main/java/org/apache/samza/startpoint/StartpointManager.java