/// must be "". The scheme must never be `nullptr`.
///
/// Every plugin fills this in `TF_InitPlugin`, using the alocator passed as
/// argument to allocate memory. After `TF_InitPlugin` finishes, core
/// TensorFlow uses the information present in this to initialize filesystems
/// for the URI schemes that the plugin requests.
///
/// All pointers defined in this structure point to memory allocated by the DSO