AddEras method
Implementation
void AddEras(int eras) {
final hr = _thisPtr.ref.vtable
.elementAt(24)
.cast<Pointer<NativeFunction<HRESULT Function(Pointer, Int32 eras)>>>()
.value
.asFunction<
int Function(Pointer, int eras)>()(_thisPtr.ref.lpVtbl, eras);
if (FAILED(hr)) throw WindowsException(hr);
}