Elementor custom widget default font family

Question

I'm creating custom widget of Elementor

I can set default font color using below code

   $this->add_group_control(
        \Elementor\Group_Control_Typography::get_type(),
        [
             'name' => 'countdown_text',
             'label' => __( 'Countdown day', 'plugin-domain' ),
             'scheme' => Elementor\Core\Schemes\Typography::TYPOGRAPHY_1, 
             'default' => '#733D1F',
             'selector' => '{{WRAPPER}} .sp-hero-countdown .sp-hero-countdown-text',
        ]
   );

I would like to set default font-family for custom title widget.font-family select drop-down

We have checked elementor developers documentation, but haven't found any solution, We want to add a default font family for the custom title widget, Please help us to resolve this issue. your help will be highly appreciated.