apply_filters( 'wpas_get_custom_fields', $this->options )
Use this to modify the custom fields array/data before it is returned to the calling function/program. An example of using filter this can be found in our Power-pack add-on (class_misc_options.php).
You can use this filter to modify the way the fields will behave when rendered – for example, making some of them mandatory or optional, changing text and labels, adding css classes etc.
Tip: Each custom field in the array has an attribute named ‘order’. This attribute controls the order in which the custom fields will be rendered on the ticket form. So, your filter function can modify this attribute for each field which will help to control the display order on the front-end ticket form.