title: Model-Identifier for Node in JavaFX 2 TreeItem
body: <p>Is there a way to store an identifier of a model object or the model object itself in a JavaFX 2 <code>TreeItem&lt;String&gt;</code>? There is just <code>Value</code> to store the text...</p>
  
  <p>I'm populating a <code>TreeView</code> from a list of model objects, and need to find it when the user clicks a node. I'm used to work with <code>Value</code> and <code>Text</code> in .NET Windows Forms or HTML and I am afraid I cannot adapt this way of thinking to JavaFX...</p>