Bug 153038 NPE when delete master page content in old report design.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/editors/schematic/editparts/ListEditPart.java
private ListHandleAdapter getListHandleAdapt( )
	{
		return (ListHandleAdapter) getModelAdapter( );
	}
	/**
	 * Insert group in list element
	 */
	public boolean insertGroup( )
	{
		return UIUtil.createGroup( getListHandleAdapt( ).getHandle( ) );
	}
	/**
	 * Insert group in list element
	 * 
	 * @param position
	 *            insert position
	 */
	public boolean insertGroup( int position )
	{
		return UIUtil
				.createGroup( getListHandleAdapt( ).getHandle( ), position );
	}
	/**
	 * Remove group
	 * 
	 * @param group
	 */
	public void removeGroup( Object group )
	{
		try