Logstash timestamp converted to UNIX nanosecond nano second time

logstash The timestamp is converted to unix nanosecond nano second time

filter {
	ruby { 
		code => "event.set('unix_nano_time',(event.get('@timestamp').to_f.round(9)*1000*1000*1000).to_i)" 
	}
}

Then take it out of the configuration unix_nano_time That is ：

"%{unix_nano_time}"