GET https://github.adaptiveinsights.com/api/v3/repos/:repo_owner/:repo_name/branches/test/protection/required_status_checks: 415 If you would like to help us test the Protected Branches API during its preview period, you must specify a custom media type in the 'Accept' header. Please see the docs for full details. 
I looked at GitHub Dev API, it said I need to provide a custom media type in Accept header
I did add "accept: application/vid.github.luke-cage-preview+json", but still no luck
Thank you for being here! This sounds like it might be a permissions issue, If you haven't already, please contact us at https://github.com/contact with the info so we can look into that further.
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