FetchOptions in CloneOptions is readonly and has not been set in constructor !

Reproduction steps

unable to set CredentialsProvider
co.FetchOptions.CredentialsProvider = (_url, _user, _cred) => new LibGit2Sharp.UsernamePasswordCredentials { Username = "username", Password = accessToken };
because the FetchOptions is null and it cannot be set in CloneOptions as it is readonly

Expected behavior

Actual behavior

Version of LibGit2Sharp (release number or SHA1)

Operating system(s) tested; .NET runtime tested

まず CloneOptions と FetchOptions の定義を見つけ、issue に示されている null FetchOptions の動作を再現します。CloneOptions がどのように構築されるかを追跡します。呼び出し元が null 参照や使用できない readonly プロパティなしで FetchOptions.CredentialsProvider を設定できれば完了です。