Form Checkbox Field is re-applying to default choice after submission

Issue Summary

Jira form field with a default choice for a checkbox field allows to un-check it , however once we submit it accepts the default choice configured. 

The issue is reproducible while creating issue form Jira issue view and portal view

Steps to Reproduce

1. Create a Form Field of Type Checkbox , lets name it "Check"
2. Add a Default Choice to the CheckBox field.
3. Link this Form to an Issue type or a Request Type.
4. Create an Issue, Fill out the form and Uncheck the CheckBox field "Check" with Default value ( make sure it's not selected ) - submit the form , create the issue.

Expected Results

The submitted form should allow selecting a blank choice.

Actual Results

The submitted form selects the Default Choice 

Workaround

• Make the field required
• Add a choice " None of the Above"
• So it cannot be a blank answer and no choice is selected.