@Nonnull
  public final ITEMTYPE createChildItem (@Nullable final DATATYPE aData)
  {
    // create new item
    final ITEMTYPE aItem = m_aFactory.create (thisAsT ());
    if (aItem == null)
      throw new IllegalStateException ("null item created!");
    aItem.setData (aData);
    internalAddChild (aItem);
    return aItem;
  }
@ Nonnull public final ITEMTYPE createChildItem ( @ Nullable final DATATYPE aData ) { final ITEMTYPE aItem = m_aFactory . create ( thisAsT ( ) ) ; if ( aItem == null ) throw new IllegalStateException ( "null item created!" ) ; aItem . setData ( aData ) ; internalAddChild ( aItem ) ; return aItem ; }
Add a child item to this item.

@param aData
the data associated with this item
@return the created TreeItem object or <code>null</code> if the ID is
already in use and bAllowOverwrite is false