public void clear() {
super.clear();
bottom = new ImmutableBitSet();
}
@Override
public void readExternal(ObjectInput objectInput) throws IOException, ClassNotFoundException {
super.readExternal(objectInput);
bottom = (ImmutableBitSet) objectInput.readObject();
}
@Override
protected void add(HierNode<T> node) {
super.add(node);
bottom.merge(node.getBitMask());
}
@Override
public void writeExternal(ObjectOutput objectOutput) throws IOException {
super.writeExternal(objectOutput);
objectOutput.writeObject(bottom);
}
