woocommerce new product type name not showing in the product page

I have created a custom product type. For that I have used this link The code that has been placed is like this

// add a product type
add_filter( 'product_type_selector', 'wdm_add_custom_product_type' );
function wdm_add_custom_product_type( $types ){
    $types[ 'wdm_custom_product' ] = __( 'Wdm Product' );
    return $types;
}
add_action( 'plugins_loaded', 'wdm_create_custom_product_type' );
function wdm_create_custom_product_type(){
     // declare the product class
     class WC_Product_Wdm extends WC_Product{
        public function __construct( $product ) {
           $this->product_type = 'wdm_custom_product';
           parent::__construct( $product );
           // add additional functions here
        }
    }
}

// add the settings under ‘General’ sub-menu
add_action( 'woocommerce_product_options_general_product_data', 'wdm_add_custom_settings' );
function wdm_add_custom_settings() {
    global $woocommerce, $post;
    echo '<div class="options_group">';

    // Create a number field, for example for UPC
    woocommerce_wp_text_input(
      array(
       'id'                => 'wdm_upc_field',
       'label'             => __( 'UPC', 'woocommerce' ),
       'placeholder'       => '',
       'desc_tip'    => 'true',
       'description'       => __( 'Enter Unique Product Code.', 'woocommerce' ),
       'type'              => 'number'
       ));

    // Create a checkbox for product purchase status
      woocommerce_wp_checkbox(
       array(
       'id'            => 'wdm_is_purchasable',
       'label'         => __('Is Purchasable', 'woocommerce' )
       ));

    echo '</div>';
}

add_action( 'woocommerce_process_product_meta', 'wdm_save_custom_settings' );
function wdm_save_custom_settings( $post_id ){
// save UPC field
$wdm_product_upc = $_POST['wdm_upc_field'];
if( !empty( $wdm_product_upc ) )
update_post_meta( $post_id, 'wdm_upc_field', esc_attr( $wdm_product_upc) );

// save purchasable option
$wdm_purchasable = isset( $_POST['wdm_is_purchasable'] ) ? 'yes' : 'no';
update_post_meta( $post_id, 'wdm_is_purchasable', $wdm_purchasable );
}

Here you can see the product type is Wdm Product but the form fields are showing in both general type and Wdm Product product type. After putting the form fields and when I am saving those fields and trying to get the product type in my product single page by using this code

$product = new WC_Product( get_the_ID() );
        print_r($product);

Its showing all the values for the product but the product type is showing blank. So can someone tell me what is the issue here? Any help and suggestions will be really appreciable. Thanks