How to use Azure DevOps Rest API to get code coverage details

I am trying to use “Code Coverage – Get Build Code Coverage” REST API, to get the code coverage details of my build:
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When I use the api and do not specify any ‘flags’ values’, I only get the summary information.

And when I add flags=7 or flags=2 or flags=4, I only get

  "value": [],
  "count": 0

My question is how can I get the coverage details of my build using REST API?