Support_path does not work for FreePBX-13

Hello:
I test webRTC gateway with FreePBX-13. I use chan_sip with support_path, it works. But when I switch to pjisp with support_path=yes, it looks failed. Actually, I set it in pjsip.registration.conf, but when i reload or restart asterisk, it still shows false.

ParameterName : ParameterValue

authenticate_qualify : false
contact : sip:[email protected]:5575
default_expiration : 3600
mailboxes :
max_contacts : 1
maximum_expiration : 7200
minimum_expiration : 60
outbound_proxy :
qualify_frequency : 60
qualify_timeout : 3.000000
remove_existing : true
support_path : false // i set it yes in conf file.
voicemail_extension :

any idea for that?