public Object clone() {
        LinkedTreeMap<K,V> clone = null;
        try {
            clone = (LinkedTreeMap<K,V>) super.clone();
        } catch (CloneNotSupportedException e) {
            throw new InternalError();
        }

        // Put clone into "virgin" state (except for comparator)
        clone.root = null;
        clone.size = 0;
        clone.modCount = 0;
        clone.entrySet = null;

        // Initialize clone with our mappings
        try {
            clone.buildFromSorted(size, entrySet().iterator(), null, null);
        } catch (java.io.IOException cannotHappen) {
        } catch (ClassNotFoundException cannotHappen) {
        }

        return clone;
    }