public static Content parse( ContentConfig xml, Schema schema )
{
if( xml instanceof EmptyContentConfig )
return new EmptyContent( ( EmptyContentConfig )xml, schema );
if( xml instanceof SimpleContentConfig )
return new SimpleContent( ( SimpleContentConfig )xml, schema );
if( xml instanceof SequenceContentConfig )
return new SequenceContent( ( SequenceContentConfig )xml, schema );
return null;
}