json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "type": "object",
      "title": "File schema.",
      "description": "Describe information needed for files in records.",
      "properties": {
          "key": {
              "type": "string"
          },
          "file_id": {
              "type": "string"
          },
          "bucket": {
              "type": "string"
          },
          "checksum": {
              "type": "string"
          },
          "size": {
              "type": "integer"
          },
          "version_id": {
              "type": "string"
          }
      }
  }