Parent issue without estimate should provide its subtasks estimates in rapid board plan mode

Problem Definition

Parent issue without estimate is not showing sub-task's estimate in the rapid board plan mode.
Currently, it's difficult to have the real total estimates for a sprint or somehow will cause confusion for users to plan ahead for next sprint.

Steps to reproduce

1. Create a Software Project.
2. Create an issue.
3. Create a sub-task from the issue, set original estimate to 3w.
4. Observe the parent issue, the Time Tracking is showing 3w as original estimate and remaining if the option to include sub-tasks is selected.
5. 
6. Create a board for this project.
7. Configure the board to estimate the issues in the Backlog using Original Time Estimate and Track time against issues using JIRA's Remaining Estimate and Time Spent fields
8. Go back to the board, choose to show detail view
9. Click on the parent issue

Expected result

The original estimate should show the total estimate for both the parent and sub task.

Actual result

The original estimate is showing unestimated.

Suggestion

Parent issue without estimate should include its sub-task's estimates in rapid board plan mode since the sub-tasks are not shown in the issue details.