ValueCountLimit and ValueLengthLimit Default Value in asp.net5

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Excuse me, when I save something in my web(Http POST). It return HTTP 400, but HTTP GET don't have, so I try to study the source code about request limit.
I want to know which file declare the default value about ValueCountLimit and ValueLengthLimit. Now, I think it is in FormReader.cs. I guess ValueCountLimit is 1024 records and ValueLengthLimit is 4mb. I'm not really sure this guess is right or not.
If you have free time. Please teach me. Thank you very much!

the reference:
https://github.com/dotnet/aspnetcore/blob/b795ac3546eb3e2f47a01a64feb3020794ca33bb/src/Http/WebUtilities/src/FormReader.cs