json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "title": "Item",
      "description": "PayPal item json schema",
      "type": "object",
      "properties": {
          "quantity": {
              "description": "Number of a particular item. 10 characters max.",
              "type": "string",
              "maxLength": 10
          },
          "name": {
              "description": "Item name. 127 characters max.",
              "type": "string",
              "maxLength": 127
          },
          "price": {
              "description": "Item cost. 10 characters max.",
              "type": "string",
              "maxLength": 10
          },
          "currency": {
              "description": "3-letter currency code.",
              "type": "string",
              "maxLength": 3
          },
          "sku": {
              "description": "Stock keeping unit corresponding (SKU) to item. 50 characters max.",
              "type": "string",
              "maxLength": 50
          },
          "description": {
              "type": "string",
              "maxLength": 127
          },
          "tax": {
              "type": "string"
          }
      },
      "required": [
          "quantity",
          "name",
          "price",
          "currency"
      ]
  }