[Checkout field editor] Add custom fields to WebHooks API

wc-add-custom-field.php

/* WooCommerce - extends woocommerce checkout field editor */
/* adds additional display areas (Admin edit user screen and WooCommerce WebHooks */
/**
* add custom checkout fields to user profile on admin edit screen
*
* @param mixed $payload
*/
function filter_woocommerce_admin_profile__custom_checkout_fields( $payload ) {
    if ( class_exists( 'WC_Checkout_Field_Editor' ) ) {
        $fieldgroups = array( 'billing'=>'billing', 'shipping'=>'shipping', 'additional'=>'additional' );
        foreach ($fieldgroups as $fieldgroup => $payload_group) {
            $fakeorder = new WC_Order();
            foreach (wc_get_custom_checkout_fields($fakeorder , array( $fieldgroup ) ) as $field_name => $field_options )  {
                //basic validation, is the field enabled
                if ( !isset($field_options['enabled'] ) || ( $field_options['enabled'] != true ) )
                    continue;
                //is the field for profile
                if ( (!isset($field_options['display_options']) ) || ( !is_array($field_options['display_options'])) || ( !in_array('profile', $field_options['display_options'])) )
                    continue;
                //passed all checks, add to payload
                /*'fields' => array(
                        'billing_first_name' => array(
                            'label'       => __( 'First name', 'woocommerce' ),
                            'description' => ''
                        ),*/
                $payload_value = array(
                    'label'       => $field_options['label'],
                    'description' => ''
                );
                if ($field_options['type'] == 'select') {
                   $payload_value['type'] = 'select';
                   $payload_value['options'] = $field_options['options'];
                }
                $payload[$payload_group]['fields'][$field_name] = $payload_value;
            }
        }
        return $payload;
    }
};
/**
* filter add for above function
*/
add_filter( 'woocommerce_customer_meta_fields', 'filter_woocommerce_admin_profile__custom_checkout_fields', 10, 1 );
/**
* filter action to add custom checkout fields to the webhook payload
*
* @param mixed $payload
* @param mixed $resource
* @param mixed $resource_id
* @param mixed $this_id
*/
function filter_woocommerce_webhook_payload__custom_checkout_fields( $payload, $resource, $resource_id, $this_id ) {
    if ( class_exists( 'WC_Checkout_Field_Editor' ) ) {
        $fieldgroups = array( 'billing'=>'billing_address', 'shipping'=>'shipping_address', 'additional'=>'additional' );
        if ($resource != 'order' || empty($resource_id)) {
            return $payload;
        }
        $order = wc_get_order( $resource_id );
        foreach ($fieldgroups as $fieldgroup => $payload_group) {
            foreach (wc_get_custom_checkout_fields($order , array( $fieldgroup ) ) as $field_name => $field_options )  {
                //basic validation, is the field enabled
                if ( !isset($field_options['enabled'] ) || ( $field_options['enabled'] != true ) )
                    continue;
                //is the field for webhooks
                if ( (!isset($field_options['display_options']) ) || ( !is_array($field_options['display_options'])) || ( !in_array('webhook', $field_options['display_options'])) )
                    continue;
                //passed all checks, add to payload
                $payload_value = get_post_meta( $resource_id, $field_name, true );
                $payload['order'][$payload_group][$field_name] = $payload_value;
                if ( is_array($payload['order']) ) {
                    $payload['order']['customer'][$payload_group][$field_name] = $payload_value;
                }
            }
        }
        return $payload;
    }
};
/**
* filter add for above function
*/
add_filter( 'woocommerce_webhook_payload', 'filter_woocommerce_webhook_payload__custom_checkout_fields', 10, 4 );
/**
* filter action to add "profile" and "webhook" to selectable display options in custom options editing screen
*
* @param mixed $options
*/
function filter_woocommerce_custom_checkout_display_options__customer_checkout_fields_profile($options) {
    $options['profile']  = __( 'Admin Profile', 'woocommerce-checkout-field-editor' );
    $options['webhook']  = __( 'Webhooks', 'woocommerce-checkout-field-editor' );
    return $options;
}
/**
* filter add for above function
*/
add_filter ('woocommerce_custom_checkout_display_options', 'filter_woocommerce_custom_checkout_display_options__customer_checkout_fields_profile', 10, 1);

WHERE SHOUL I ADD THIS CODE? IN HERE I WILL HAVE TO MODFY TO CONNECT TO AS CUSTOM POST TYPE?