It looks like you'e trying to call the API HTTPS endpoints directly using a third party HTTP client. As we didn't make the client, we can't help with it specifically, but we can try to offer some guidance on how to use the API.
content Type: System.Net.Http.HttpContent The HTTP request content sent to the server.
So, it looks like you need to construct and supply a HttpContent there. You didn't mention which API or endpoint you're trying to use, so you should refer to the relevant API documentation for the endpoint you're trying to see what the right values to send up are for your case.
Re: How do I set up HttpContent for my HttpClient PostAsync for dropbox api
I'm not sure I understand your question. Can you clarify? Thanks in advance!
Also, again (per your previous thread) note that you can't use an "access_token" URL parameter to pass up your access token to API v2. You can only use an "Authorization" header or an "authorization" URL parameter.
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