No persistentqueue attributes in outputs.conf. How to configure data buffering on Heavy Forwarder ?

I was referring to this link, [https://wiki.splunk.com/Community:Best_Practice_For_Configuring_Syslog_Input][1] to configure data buffering on Heavy Forwarder. The instructions provided talk about configuring the below attributes in outputs.conf, 1. maxQueueSize = integer 2. usePersistentQueue = true/false 3. persistentQueuePath = absolute_path_that_must_exist 4. maxPersistentQueueSizeInMegs = integer However, except maxQueueSize, no other attributes can be found in the outputs.conf file. Please advise how can I configure data buffering in this case. [1]: https://wiki.splunk.com/Community:Best_Practice_For_Configuring_Syslog_Input