It's better to show a warning message like The default implementation of AbstractTreeModel.getPath() is inefficient, overriding this method is suggested when the method is called.

The reasons are:

• Although we hint the potential problem in documentation , users mostly don't read when it works.
• When users extend AbstractTreeModel, it usually means they need something other than DefaultTreeModel. It mostly means they should override getPath() in their case.
• Show the warning may save debugging time for us and users.