Event fired when the topology closes.
@since 2.4.0
Create the event.
@example Create the event.
TopologyClosed.new(topology)
@param [ Integer ] topology The topology.
Returns a concise yet useful summary of the event.
@return [ String ] String summary of the event.
@note This method is experimental and subject to change.
@since 2.7.0 @api experimental
[Validate]