code: public boolean isEmpty() {
  		int snapshotSize = cleared ? 0 : snapshot.size();
  		//nothing in both
  		if ( snapshotSize == 0 && currentState.isEmpty() ) {
  			return true;
  		}
  		//snapshot bigger than changeset
  		if ( snapshotSize > currentState.size() ) {
  			return false;
  		}
  		return size() == 0;
  	}
docs: Whether this association contains no rows.
  
  @return {@code true} if this association contains no rows, {@code false} otherwise