Pie Chart Gadgets display duplicate values for a custom field configured with more than one context

Summary

Pie Chart Gadgets do not display correct results when the selected statistic type is a custom field configured for more than one context with the same custom field values

Environment

• JIRA version 6.4.3
• JIRA version 7.1.9
• Jira version 8.13.2

Steps to Reproduce

1. Create a Custom field(tested with check box type) and associate it to a project.
2. Create a new context in the same custom field with the same values and associate it to a different project as shown in below image
3. Create some issues by selecting values for the custom field.
4. Create a filter for this which includes both the project which is using this custom field
5. Add this filter to Pie Chart Gadget, and set this custom field as the statistics type

Expected Results

The pie chart displays one row per custom field option.

Actual Results

The pie chart displays multiple rows per custom field option as shown in the screenshot below

Workaround

Create separate filter for each Project which uses custom field with context and associate them in different Pie Chart