How to use IMemoryBufferByteAccess with C++/WinRT

IMemoryBufferByteAccess.cpp

#include "winrt/Windows.Foundation.h"

struct __declspec(uuid("5b0d3235-4dba-4d44-865e-8f1d0e4fd04d")) __declspec(novtable) IMemoryBufferByteAccess : ::IUnknown
{
    virtual HRESULT __stdcall GetBuffer(uint8_t** value, uint32_t* capacity) = 0;
};

using namespace winrt;
using namespace Windows::Foundation;

int main()
{
    init_apartment();

    MemoryBuffer buffer(10);
    IMemoryBufferReference ref = buffer.CreateReference();
    WINRT_ASSERT(ref.Capacity() == 10);

    {
        auto interop = ref.as<IMemoryBufferByteAccess>();

        uint8_t* value{};
        uint32_t value_size{};
        check_hresult(interop->GetBuffer(&value, &value_size));
        WINRT_ASSERT(value_size == 10);

        sprintf_s(reinterpret_cast<char*>(value), value_size, "C++/WinRT");
    }

    {
        auto interop = ref.as<IMemoryBufferByteAccess>();

        uint8_t* value{};
        uint32_t value_size{};
        check_hresult(interop->GetBuffer(&value, &value_size));
        WINRT_ASSERT(value_size == 10);

        printf("%s\n", reinterpret_cast<char*>(value));
    }
}

@Youw unknwn.h will suffice.