Java内部类this$0字段产生的一个bug

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public class BinomialHeap<E> implements
Cloneable {

        transient
BinomialHeapEntry head; // 根表中的第一个元素

        int
size;                         // 整个二项堆的大小（结点数）

        private
class BinomialHeapEntry {

        E element;

        transient
BinomialHeapEntry parent = null, child = null,

                sibling = null;

        transient
int degree = 0;

                private
BinomialHeapEntry(E element) {

            this.element = element;

        }

                // 获得孩子结点的迭代器

                private
Iterable<BinomialHeapEntry> children {...}

        }

        @Override

    public
BinomialHeap<E> clone() {

        // TODO Auto-generated method stub

        BinomialHeap<E> clone;

        try
{

            clone = (BinomialHeap<E>) super.clone();

        } catch
(CloneNotSupportedException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

            throw
new InternalError();

        }

        BinomialHeapEntry newHead = null, curRoot = null;

                // 遍历根表

        Iterator<HeapEntry<E>> rootIt = this.roots().iterator();

        while(rootIt.hasNext()){

            BinomialHeapEntry root = (BinomialHeapEntry) rootIt.next();

                        // 拷贝根节点下的整棵二项树<br>                        <span style="color: rgb(255, 0, 0);">// BUG引入的地方</span>

            BinomialHeapEntry newRoot = cloneBinomialTree(root);

            if(curRoot == null){

                newHead = newRoot;

            } else
{

                curRoot.sibling = newRoot;

            }

            curRoot = newRoot;

        }

        clone.head = newHead;

        return
clone;

    }

        // 拷贝根节点（含根节点）下的整棵子树

    private
BinomialHeapEntry cloneBinomialTree(BinomialHeapEntry root){

        BinomialHeapEntry newRoot = new
BinomialHeapEntry(root.element());

        BinomialHeapEntry curChild = null;

                // 遍历根节点的所有孩子结点

        Iterator<HeapEntry<E>> childIt = root.children().iterator();

        while(childIt.hasNext()){

            BinomialHeapEntry child = (BinomialHeapEntry) childIt.next();

            // 递归拷贝孩子节点下的子树

                        BinomialHeapEntry newChild = cloneBinomialTree(child);

            newChild.parent = newRoot;

            if(curChild == null){

                newRoot.child = newChild;

            } else
{

                curChild.sibling = newChild;

            }

            curChild = newChild;

        }

        newRoot.degree = root.degree;

        return
newRoot;

    }

}