sanitize_widget_instance example

'capability' => 'edit_theme_options',
            'default'    => array(),
        );

        if ( preg_match( $this->setting_id_patterns['sidebar_widgets'], $id, $matches ) ) {
            $args['sanitize_callback']    = array( $this, 'sanitize_sidebar_widgets' );
            $args['sanitize_js_callback'] = array( $this, 'sanitize_sidebar_widgets_js_instance' );
            $args['transport']            = current_theme_supports( 'customize-selective-refresh-widgets' ) ? 'postMessage' : 'refresh';
        } elseif ( preg_match( $this->setting_id_patterns['widget_instance'], $id, $matches ) ) {
            $id_base                      = $matches['id_base'];
            $args['sanitize_callback']    = function( $value ) use ( $id_base ) {
                return $this->sanitize_widget_instance( $value, $id_base );
            };
            $args['sanitize_js_callback'] = function( $value ) use ( $id_base ) {
                return $this->sanitize_widget_js_instance( $value, $id_base );
            };
            $args['transport']            = $this->is_widget_selective_refreshable( $matches['id_base'] ) ? 'postMessage' : 'refresh';
        }

        $args = array_merge( $args, $overrides );

        /** * Filters the common arguments supplied when constructing a Customizer setting. * * @since 3.9.0 * * @see WP_Customize_Setting * * @param array $args Array of Customizer setting arguments. * @param string $id Widget setting ID. */