Custom Fields Mapping describes how custom fields seen by user (e.g. contact custom field Role in organisation)
are mapped to custom field objects in Search API backend (e.g. contact:12345).
Custom Fields Mapping API returns list of all custom fields defined on account
for given entity (lead/contact/deal), alongside with additional meta-information
(custom field type, id to use within search API, user-provided name).
There is one mapping API endpoint for each entity type:
Deal custom fields mapping
Lead custom fields mapping
Contact custom fields mapping
CustomField type consists of following attributes:
ID of this custom field in Base backend systems
User-defined custom field name, e.g. Role in organisation