POST /v1/marketplaces/{marketplace_id}/buyers { "first_name": "Fabiano", "last_name": "Cruz", "taxpayer_id": "63488360024", "description": "Customer for jack@example.com", "email": "fabiano@example.com", "metadata": "twitter.id": "1234987650", "facebook.user_id": "0192837465", "my-own-customer-id": "12345" } }