* <i>except</i> new child nodes are also added to a list, which is used to
* support the TreeNode interface.
*/
public StackNode getChild(MethodKey methodKey) {
StackNode treeNode = null;
synchronized (children) {
treeNode = (StackNode) children.get(methodKey);
if (treeNode == null) {
treeNode = new StackTreeNode(methodKey, this);
childList.add(treeNode);