public Expression getUndefinedValue(Factory factory) {
	if (undefinedValue == null) return tag.getAttributeUndefinedValue(factory);
	return factory.createLiteral(undefinedValue, factory.TRUE());
    }
public Expression getUndefinedValue ( Factory factory ) { if ( undefinedValue == null ) return tag . getAttributeUndefinedValue ( factory ) ; return factory . createLiteral ( undefinedValue , factory . TRUE ( ) ) ; }
@return Returns the defaultValue.