Workspaces: Create workspace and custom block via JSON?

I want to create a Workspace with a Custom Block for my mobile app.

What are the ‘content’ and ‘custom_blocks’ JSON supposed to look like?

 "content": "[{\"id\":\"nKKr6fjgjb\",\"type\":\"card\",\"data\":{\"card_name\":\"Ledgers\",\"col\":4}},{\"id\":\"p7NY6MHe2Y\",\"type\":\"card\",\"data\":{\"card_name\":\"Financial Statements\",\"col\":4}},{\"id\":\"3AK1Zf0oew\",\"type\":\"card\",\"data\":{\"card_name\":\"Profitability\",\"col\":4}},{\"id\":\"Q_hBCnSeJY\",\"type\":\"card\",\"data\":{\"card_name\":\"Other Reports\",\"col\":4}}]",
 "creation": "2024-01-05 16:09:16.766939",
 "custom_blocks": [],
 "docstatus": 0,
 "doctype": "Workspace",
 "for_user": "",