json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "title": "File schema",
      "description": "Description of a file, that is attached to a step",
      "file": {
          "type": "object",
          "description": "description of a file",
          "properties": {
              "path": {
                  "type": "string",
                  "description": "Path of the file"
              }
          },
          "required": [
              "path"
          ],
          "additionalProperties": false
      },
      "properties": {
          "file": {
              "$ref": "#/file"
          }
      },
      "required": [
          "file"
      ]
  }