Pppoe keepalive_adaptive

Is the option keepalive_adaptive still a valid option in the network configuration file? I don't see any official documentation about keepalive_adaptive.

config interface 'wan'
	option device 'eth0.835'
	option proto 'pppoe'
	option username 'user'
	option password 'password'
	keepalive_adaptive '1'
	option ipv6 '1'
	option peerdns '0'
	list dns ''
	list dns ''

Somebody suggested to me to add keepalive_adaptive '1' to avoid the keepalive with LCP Echo Request when there is active traffic with the advantage of avoid missing replay during massive uploads and downloads and connection hungup.
My router behaviour with 21.02.3 and without keepalive option specified is to send a LCP Echo Request every one second, don't know what is the default replay failure number before it close the connection.