Customer properties:

This will collect information through the custom field in classhub registration page and save it under the custom fields in inTennis

CLASS_REGISTRATION_SAVE_CUSTOM_FIELD_TO_CONTACT_ENABLED true
CLASS_REGISTRATION_SAVE_CUSTOM_FIELD_TO_CONTACT_MAPPING 3,1
(3 is the custom field and 1 is the custom field in inTennis )
CLASS_REGISTRATION_SAVE_CUSTOM_FIELD_TO_CONTACT_MAPPING2 5,7