Reproduce steps:
With invoice showcase

• goto Approve Invoice task
• enter "true" in "Do you approve" filed
• save
• switch view and go back to form tab
  --> value "true" is saved and I can complete button is enabled
• enter "false" in "Do you approve" filed
• save
• switch view and go back to form tab
  --> value "true" is saved and I can complete button is disabled

Problem:
ng-invalid-required is set when I enter "false"

Expected behavior:
ng-valid-required