C# gRPC code first API streaming from client

Question

Need a little help. I am using code first approach to gRPC. Here is my service definition:

[ServiceContract]
public interface IFileStorageService
{
    [OperationContract]
    Task<StoreFileResponse> StoreFile(IAsyncStreamReader<FileChunk> requestStream, CallContext context);
}

I want to be able to create a code first client by using following method

serviceCollection.AddCodeFirstGrpcClient<IFileStorageService>(...)

My problem is that when I then try to use the client by injecting IFileStorageService in my client app, I have no idea where to get the IAsyncStreamReader from.

Can anyone help me ? Cheers!