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

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

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

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

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