could not set port attribute extra-dhcp-opt

when use cli set port attribute extra-dhcp-opt, returns error.
$ openstack port set port1 --extra-dhcp-opt opt_name='mtu',opt_value='1300'
usage: openstack port set [-h] [--device <device-id>]
                          [--device-owner <device-owner>]
                          [--vnic-type <vnic-type>] [--host <host-id>]
                          [--enable | --disable] [--name <name>]
                          [--fixed-ip subnet=<subnet>,ip-address=<ip-address>]
                          [--no-fixed-ip]
                          [--binding-profile <binding-profile>]
                          [--no-binding-profile]
                          [--security-group <security-group>]
                          [--no-security-group]
                          <port>
openstack port set: error: unrecognized arguments: --extra-dhcp-opt opt_name=mtu,opt_value=1300