code: public IModel<List<T>> getChildChoices()
  	{
  		final T selectedRootOption = TwoDropDownChoicesModel.this.selectedRootOption;
  		final IModel<List<T>> childChoices = new AbstractReadOnlyModel<List<T>>()
  		{
  
  			/** The Constant serialVersionUID. */
  			private static final long serialVersionUID = 1L;
  
  			/**
  			 * {@inheritDoc}
  			 */
  			@Override
  			public List<T> getObject()
  			{
  				List<T> models = getModelsMap().get(selectedRootOption);
  				if (models == null)
  				{
  					models = Collections.emptyList();
  				}
  				return models;
  			}
  
  		};
  		return childChoices;
  	}
docs: Gets the child choices.
  
  @return the child choices