Problem is, the God Folder dates back to Vista and it is the Windows 10 Creators Update that began setting that field to NULL. Apparently the author of that change did not foresee any backward compatibility issues.
See my other comment for the details, I believe now that the field was actually not set to null, the returned structure has a union which is documented to be able to be of different types. It's surely the type STRRET_CSTR that wasn't covered by Java, the API is then valid before and after the update, returning the structure with STRRET_CSTR and zeroes in the union is valid.