public void collect(CheckedTreeNode node) {
        if (node.isLeaf()) {
          Object userObject = node.getUserObject();
          if (node.isChecked() && userObject != null && nodeType.isAssignableFrom(userObject.getClass())) {
            //noinspection unchecked
            final T value = (T)userObject;
            if (filter != null && !filter.accept(value)) return;
            nodes.add(value);
          }
        }
        else {
          for (int i = 0; i < node.getChildCount(); i++) {
            final TreeNode child = node.getChildAt(i);
            if (child instanceof CheckedTreeNode) {
              collect((CheckedTreeNode)child);
            }
          }
        }
      }
public void collect(CheckedTreeNode node)