Assistance with converting CURL request into PowerQuery

[jnickell]

I have a successful CURL request to Box.com's API, but I'm uncertain how to translate that into a successful PowerQuery  statement.

curl --location --request "POST" --header "Content-Type: application/x-www-form-urlencoded" --data-urlencode "client_id=<clientID>" --data-urlencode "client_secret=<ClientSecret" --data-urlencode "grant_type=client_credentials" --data-urlencode "box_subject_type=enterprise" --data-urlencode "box_subject_id=<companyID>" "https://api.box.com/oauth2/token"

I've successfully used the result that was returned by this CURL query to get a file from Box.

What I have so far, gets me a 400 error message.

let
  LoginURL = "https://api.box.com/oauth2/token",
  PostBody = [
      #"client_id" = "<clientID>",
      #"client_secret" = "<clientsecret>",
      #"grant_type" = "client_credentials",
      #"box_subject_type" = "enterprise",
      #"box_subject_id" = "<companyID>"
    ],
  Header = [#"content-type"="application/x-www-form-urlencoded"],
  PostBodyEncoded = Uri.BuildQueryString(PostBody),
  out = Json.Document(Web.Contents(LoginURL,[Content=Json.FromValue(PostBodyEncoded),Headers=Header]))
  
in
  out

 I don't have much experience with CURL or Web.Contents so it's been painful to get to this point.  
Box's documentation on the API is focused on SDK implementations
https://box.dev/guides/authentication/jwt/without-sdk//#code-samples
This is my second time to try and post this. Hopefully this time it will actually go through.  I appreciate any assistance you might be able to give. 

[jnickell · Accepted solution]

I guess sleep is a good thing.  I took another look at this forum post and was able get a working configuration in my situation as well.
https://community.powerbi.com/t5/Desktop/requests-to-a-JWT-API-token/td-p/1097823

The difference was changing 

Content=Json.FromValue(PostBodyEncoded)

 to

Content=Text.ToBinary(PostBodyEncoded)