WC_Shipping_Method::init_instance_settings PHP Method

    public function init_instance_settings()
    {
        $this->instance_settings = get_option($this->get_instance_option_key(), null);
        // If there are no settings defined, use defaults.
        if (!is_array($this->instance_settings)) {
            $form_fields = $this->get_instance_form_fields();
            $this->instance_settings = array_merge(array_fill_keys(array_keys($form_fields), ''), wp_list_pluck($form_fields, 'default'));
        }
    }