{
  "type": "object",
  "properties": {
    "order_id": { "type": "string", "minLength": 4, "maxLength": 8 },
    "items": {
      "type": "array",
      "minItems": 1,
      "maxItems": 3,
      "items": {
        "type": "object",
        "properties": {
          "sku": { "type": "string", "minLength": 1, "maxLength": 6 },
          "qty": { "type": "integer" }
        },
        "required": ["sku", "qty"],
        "additionalProperties": false
      }
    },
    "note": { "type": ["string", "null"], "maxLength": 10 }
  },
  "required": ["order_id", "items", "note"],
  "additionalProperties": false
}