Woocommerce Additional Information Tab: Adding product custom field value

I have the following code working to create the Additional information tab in woocommerce with my own values however I want to pull the information from the built-in product custom field.

add_filter( 'woocommerce_display_product_attributes', 'custom_product_additional_information', 10, 2 );
function custom_product_additional_information( $product_attributes, $product ) {
    // First row
    $product_attributes[ 'attribute_' . 'custom-one' ] = array(
        'label' => __('Label One'),
        'value' => __('Value 1'),
    );

    // Second row
    $product_attributes[ 'attribute_' . 'custom-two' ] = array(
        'label' => __('Label Two'),
        'value' => __('Value 2'),
    );

    return $product_attributes;
}

This is the current code I use to output the custom field, how do I output this in Value 1 in functions.php file in the working code above?

echo get_post_meta( get_the_ID(), 'Size', true );

Answer

Try the following replacing in your code:

        'value' => __('Value 1'),

with:

        'value' => $product->get_meta('Size'),

It should work.