Hello, we're integrating with ZohoBooks using APIs, the first step is to setup accounting fields by getting accounts/contacts (as vendors for us) and all other accounting fields as we call them. getting accounts/contacts and some other fields is straightforward but from Zoho UI we can see custom fields on expenses/bills levels where the user can add his custom field and even mark them as mandatory/optional then creating expenses will depend on this.Ffrom APIs perspective we can't find any API under custom fields section (https://www.zoho.com/books/api/v3/custom-fields/#overview)

I read somewhere that there is an API called /custom-fields and the response would be like:
{ "custom_fields": [ { "id": 1, "name": "Custom Field 1", "label": "Custom Field Label 1", "type": "Text", "required": false, "visible": true, "default_value": "", "created_time": "2023-01-01T00:00:00+00:00", "modified_time": "2023-01-01T00:00:00+00:00" }, { "id": 2, "name": "Custom Field 2", "label": "Custom Field Label 2", "type": "Number", "required": false, "visible": true, "default_value": "", "created_time": "2023-01-01T00:00:00+00:00", "modified_time": "2023-01-01T00:00:00+00:00" } ] }