def refund_id=(refund_id)
      if refund_id.nil?
        fail ArgumentError, "refund_id cannot be nil"
      end

      if refund_id.to_s.length < 1
        fail ArgumentError, "invalid value for 'refund_id', the character length must be great than or equal to 1."
      end

      @refund_id = refund_id
    end
def refund_id=(refund_id)
      if refund_id.nil?
        fail ArgumentError, "refund_id cannot be nil"
      end

      if refund_id.to_s.length < 1
        fail ArgumentError, "invalid value for 'refund_id', the character length must be great than or equal to 1."
      end

      @refund_id = refund_id
    end
Custom attribute writer method with validation
 @param [Object] refund_id Value to be assigned