is FlushOptions missing Send and Sync impl's?

[jansegre]

I noticed that Options, ReadOptions and WriteOptions all implement Send+Sync on this section of db_options.rs:

// Safety note: auto-implementing Send on most db-related types is prevented by the inner FFI
// pointer. In most cases, however, this pointer is Send-safe because it is never aliased and
// rocksdb internally does not rely on thread-local information for its user-exposed types.
unsafe impl Send for Options {}
unsafe impl Send for WriteOptions {}
unsafe impl Send for BlockBasedOptions {}
unsafe impl Send for CuckooTableOptions {}
unsafe impl Send for ReadOptions {}
unsafe impl Send for IngestExternalFileOptions {}
unsafe impl Send for CacheWrapper {}

// Sync is similarly safe for many types because they do not expose interior mutability, and their
// use within the rocksdb library is generally behind a const reference
unsafe impl Sync for Options {}
unsafe impl Sync for WriteOptions {}
unsafe impl Sync for BlockBasedOptions {}
unsafe impl Sync for CuckooTableOptions {}
unsafe impl Sync for ReadOptions {}
unsafe impl Sync for IngestExternalFileOptions {}
unsafe impl Sync for CacheWrapper {}

Should FlushOptions be there too? Or was it left out intentionally?