def sort_field=(sort_field)
      validator = EnumAttributeValidator.new('String', ["DEFAULT", "CREATED_AT"])
      unless validator.valid?(sort_field)
        fail ArgumentError, "invalid value for 'sort_field', must be one of #{validator.allowable_values}."
      end
      @sort_field = sort_field
    end
def sort_field=(sort_field)
      validator = EnumAttributeValidator.new('String', ["DEFAULT", "CREATED_AT"])
      unless validator.valid?(sort_field)
        fail ArgumentError, "invalid value for 'sort_field', must be one of #{validator.allowable_values}."
      end
      @sort_field = sort_field
    end
Custom attribute writer method checking allowed values (enum).
 @param [Object] sort_field Object to be assigned