code: function checkUnknown(json, schemaKeys) {
      var jsonKeys = [];
      for (var k in json) {
        if (schemaKeys.indexOf(k) === -1) {
          throw new ValidationException(
            "The key: " +
              k +
              " is not declared in the schema. Declare it or allow unknown keys."
          );
        }
      }
    }
docs: Check for unknown keys
  @param  {[type]} json       [description]
  @param  {[type]} schemaKeys [description]
  @return {[type]}            [description]