if (hostTree.getModel().equals(source))
if (hostTree.getModel().equals(source)) {
  public void treeNodesRemoved(TreeModelEvent e) {    Object source = e.getSource();    if (hostTree.getModel().equals(source))      treeNodesRemovedFromHostTree(e);    else if (nodeTree.getModel().equals(source))      treeNodesRemovedFromNodeTree(e);    experimentBuilder.setModified(true);  }