Flag indicating if this layout handles exceptions
        false if this layout handles exceptions
 If this layout handles the exception object contained within LoggingEvent, then the layout should return false. Otherwise, if the layout ignores the exception object, then the layout should return true. 
 Set this value to override a this default setting. The default value is true, this layout does not handle the exception. 
LayoutSkeleton Class | log4net.Layout Namespace