@classmethod
def from_port_request(cls, context, port_uuid, port_resource_request):
    """Init the group from the resource request of a neutron port

        :param context: the request context
        :param port_uuid: the port requesting the resources
        :param port_resource_request: the resource_request attribute of the
                                      neutron port
        For example:

            port_resource_request = {
                "resources": {
                    "NET_BW_IGR_KILOBIT_PER_SEC": 1000,
                    "NET_BW_EGR_KILOBIT_PER_SEC": 1000},
                "required": ["CUSTOM_PHYSNET_2",
                             "CUSTOM_VNIC_TYPE_NORMAL"]
            }
        """
    obj = cls(context=context, use_same_provider=True, resources=
        port_resource_request['resources'], required_traits=set(
        port_resource_request.get('required', [])), requester_id=port_uuid)
    obj.obj_set_defaults()
    return obj
