Exposing a List of Entities

So I have an Employee entity that looks something like this.

class Employee::Entity < Grape::Entity
  expose :id, :name, :company
end

The Employee has tons of clock ins to the timecard system. The entity for a Clockin is something like:

class Clockin::Entity < Grape::Entity
  expose :id, :year, :date, :code, :description
end

Displaying all of the clock ins for an employee is easy enough. How would I go about segregating them by year, though?

My first thought was adding something like this to the Employee entity

expose :clockins do |employee, options|
  employee.clockins.group_by { |c| c[:year] }
end

That does get the correct data, but it's not presented correctly.

Start with the Employee::Entity and Clockin::Entity examples in the issue, then inspect how grouped clockins are rendered by Grape::Entity. Determine the expected serialized representation for clockins grouped by year and verify that the output is presented in that structure.