Professors Post Type register on mu-plugins

    //Register Professors Post Type
    register_post_type('professor', array(  
        'show_in_rest' => true,
        'supports' => array('title', 'editor'), 
        'rewrite' => array('slug' => 'professors'),            
        'has_archive' => true,
        'public' => true,
        'labels' => array(
            'name' => 'Professors',
            'add_new' => 'Add New Professor',            
            'add_new_item' => 'Add New Professors',
            'edit_item' => 'Edit Professor',
            'all_items' => 'All Professors',
            'singular_name' => 'Professor'
        ),
        'menu_icon' => 'dashicons-welcome-learn-more'
    ));