json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "title": "Vault Collection Expression",
      "type": "object",
      "properties": {
          "vaults": {
              "type": "array",
              "items": {
                  "type": "string"
              },
              "_uniqueItems": true,
              "minItems": 1
          }
      },
      "required": [
          "vaults"
      ],
      "additionalProperties": false
  }