This filter can be used for adding or deleting field type in the form.
Changelog
Since 7.0.0 version
Parameters
$allowedFieldsType (type: array) - the array of the allowed fields of the forms
Usage
add_filter("wpdiscuz_allowed_form_field", function ($allowedFieldsType) {
$allowedFieldsType[] = "MyCustomFieldClass";
return $allowedFieldsType;
});