<PackageReference Include="Microsoft.AspNet.WebApi.Client" Version="4.0.20505" />

HttpContentMultipartExtensions

public static class HttpContentMultipartExtensions
Extension methods to read MIME multipart entities from HttpContent instances.
public static bool IsMimeMultipartContent(this HttpContent content)

Determines whether the specified content is MIME multipart content.

public static bool IsMimeMultipartContent(this HttpContent content, string subtype)

Determines whether the specified content is MIME multipart content with the specified subtype. For example, the subtype mixed would match content with a content type of multipart/mixed.

public static Task<IEnumerable<HttpContent>> ReadAsMultipartAsync(this HttpContent content, IMultipartStreamProvider streamProvider, int bufferSize)