curl --request GET \
  --url https://{FUSION HOST}/api/subscriptions/_schema \
  --header 'Authorization: Basic <encoded-value>'

{
  "type": "string",
  "title": "<string>",
  "description": "<string>",
  "required": [
    "<string>"
  ],
  "properties": {},
  "additionalProperties": {},
  "minProperties": 123,
  "maxProperties": 123,
  "definitions": {},
  "category": "<string>",
  "categoryPriority": 123,
  "hints": [
    "<string>"
  ],
  "unsafe": true,
  "default": {},
  "oneOf": [
    {
      "type": "string",
      "title": "<string>",
      "description": "<string>",
      "default": {},
      "category": "<string>",
      "categoryPriority": 123,
      "hints": [
        "<string>"
      ],
      "unsafe": true
    }
  ],
  "propertyGroups": [
    {
      "label": "<string>",
      "properties": [
        "<string>"
      ]
    }
  ]
}