/**
  * Extend to start listening to the models if necessary.
  *
  * @see org.eclipse.persistence.tools.workbench.utility.Model#addTreeChangeListener(String,
  *     TreeChangeListener)
  */
 public synchronized void addTreeChangeListener(String treeName, TreeChangeListener listener) {
   if (treeName == VALUE && this.hasNoListeners()) {
     this.engageModels();
   }
   super.addTreeChangeListener(treeName, listener);
 }
 /**
  * Extend to start listening to the models if necessary.
  *
  * @see
  *     org.eclipse.persistence.tools.workbench.utility.Model#addTreeChangeListener(TreeChangeListener)
  */
 public synchronized void addTreeChangeListener(TreeChangeListener listener) {
   if (this.hasNoListeners()) {
     this.engageModels();
   }
   super.addTreeChangeListener(listener);
 }