in achievements-server/src/main/java/org/jetbrains/buildserver/achievements/impl/ProductivityBoost.java [56:59]
public boolean shouldGrantAchievement(@NotNull SUser user, @NotNull UserEvents events, @NotNull String lastEventName, @Nullable Object additionalData) {
String watchedEvent = getId() + ":changeAdded";
return events.getNumberOfEvents(watchedEvent) >= 20;
}