json_schema: {
      "title": "mediaInfo chart value",
      "type": "object",
      "$schema": "http://json-schema.org/draft-04/schema",
      "description": "The value object contains information for popup windows about how charts should be constructed.",
      "properties": {
          "fields": {
              "type": "array",
              "description": "An array of strings, with each string containing the name of a field to display in the chart.",
              "items": {
                  "type": "string"
              },
              "_uniqueItems": true
          },
          "normalizeField": {
              "type": "string",
              "description": "An optional string containing the name of a field. The values of all fields in the chart will be normalized (divided) by the value of this field."
          },
          "tooltipField": {
              "type": "string",
              "description": "String value indicating the tooltip for a chart specified from another field. This field is needed when related records are not used. It is used for showing tooltips from another field in the same layer or related layer/table."
          }
      },
      "required": [
          "fields"
      ],
      "additionalProperties": false
  }