Add custom tag on post slider of Master Slider

class-master-slider-override.php

<?php

/**
 *
 * @wordpress-plugin
 * Plugin Name:       Custom Tags For Master Slider
 * Plugin URI:        http://uditrawat.com
 * Description:       Custom Tags For Master Slider
 * Version:           1.3
 * Author:            Udit Rawat
 * Author URI:        http://uditrawat.com
 * Text Domain:       emerico
 */
class HomeSlider
{
    /**
     * Instance of this class.
     *
     * @since    1.0.0
     *
     * @var      object
     */
    protected static $instance = null;

    /**
     * Return an instance of this class.
     *
     * @since     1.0.0
     *
     * @return    object    A single instance of this class.
     */
    public static function get_instance()
    {

        // If the single instance hasn't been set, set it now.
        if (null == self::$instance) {
            self::$instance = new self;
        }

        return self::$instance;
    }

    /**
     * Class constructor
     *
     * @since     1.0.0
     */
    private function __construct()
    {
        // Add new tag to master slider tag list
        add_filter('masterslider_post_slider_tags_list', [$this, 'master_slider_add_project_tags'], 10, 1);

        // Add value of newly added tag
        add_filter('masterslider_get_template_tag_value', [$this, 'master_slider_tag_values'], 10, 4);

    }

    /**
     * @param $tags
     * @return array
     */
    function master_slider_add_project_tags($tags)
    {
        $tags[] = [
            'name' => 'project_business_partners',
            'label' => __('Project Business Partners', 'emerico'),
            'type' => 'post' // POST_TYPE
        ];
        $tags[] = [
            'name' => 'project_npo_partners',
            'label' => __('Project NPO Partners', 'emerico'),
            'type' => 'post' // POST_TYPE
        ];
        $tags[] = [
            'name' => 'project_call_to_action',
            'label' => __('Project Call To Action', 'emerico'),
            'type' => 'post' // POST_TYPE
        ];
        return $tags;
    }

    /**
     * @param $value
     * @param $tag_name
     * @param $project
     * @param $args
     * @return bool|mixed|null|string|void
     */
    function master_slider_tag_values($value, $tag_name, $project, $args)
    {
        switch ($tag_name) {
            case 'project_business_partners':
                $value = 'Custom value here'; // CUSTOM VALUE FOR TAG HERE
                break;
            case 'project_npo_partners':
                $value = 'Custom value here'; // CUSTOM VALUE FOR TAG HERE
                break;
            case 'project_call_to_action':
                $value = 'Custom value here'; // CUSTOM VALUE FOR TAG HERE
                break;
        }

        return $value;
    }

}

if(class_exists('Master_Slider'))
    add_action( 'plugins_loaded', array( 'HomeSlider', 'get_instance' ) );