Created vs. Resolved gadget should respect the Cumulative Totals option set before the upgrade

Problem Definition

After migrate JIRA from 6.x to 7.0.x, the Created vs. Resolved gadget is not respecting the "Cumulative Totals" option previously set.

In JIRA 6.x, the gadget had the “Cumulative Totals” option where you can set "Yes" or "No", and in JIRA 7.x has a “Collection Operation” with “Count” or “Cumulative” options.
If you set "Yes" for the “Cumulative Totals” option in JIRA 6.x, after migrate you expect to see the Cumulative option there, however the system is changing it to "Count" instead, so you need to manually edit each Dashboard back to the Cumulative option, which can be a pain if you have a quite few Dashboards.

Steps to Reproduce

1. Add a new "Created vs. Resolved gadget" in JIRA 6.4.12
2. Select a desired project name (e.g TEST) and change Cumulative Totals: to YES value
3. Save the gadget and create a backup out
4. Restore the backup to JIRA 7.0.10
5. Navigate back to the Dashboard page, you will get the error message below:

   Unfortunately, one or more of your preferences are now unavailable. Please update your preferences, or remove gadget by clicking delete from the title bar above.
   Invalid field. Valid values are [count, cumulative].
   

Expected Results

If the previously version was configured with Cumulative Totals = Yes, it would be great if the new version (7.0.x) could keep the user's choice by setting Collection Operation = Cumulative.
Or maybe we can add an option to define the default value from this field in JIRA, so all dashboards can use the default value.

Actual Results

In JIRA 6, it was configured with Cumulative Totals = Yes but in the latest JIRA 7, it shows errors.

Workaround

Ask all users to manually edit their Dashboards in case they are using this gadget.