def application_calendar(application_calendar_id)
      do_request do
        body = {
          client_id: @api_client.id,
          client_secret: @api_client.secret,
          application_calendar_id: application_calendar_id,
        }

        @response = @api_client.request(:post, "/v1/application_calendars", body: body)
        Credentials.new(OAuth2::AccessToken.from_hash(@api_client, @response.parsed))
      end
    end
def application_calendar(application_calendar_id)
      do_request do
        body = {
          client_id: @api_client.id,
          client_secret: @api_client.secret,
          application_calendar_id: application_calendar_id,
        }

        @response = @api_client.request(:post, "/v1/application_calendars", body: body)
        Credentials.new(OAuth2::AccessToken.from_hash(@api_client, @response.parsed))
      end
    end
Internal: Obtains access to an application calendar

 application_calendar_id - A String to identify the application calendar
                           which is to be accessed.

 Returns Hash of token elements to allow client to update in local store
 for user

 Raises Cronofy::CredentialsMissingError if no credentials available.