Fix deserialization of extra_headers.
kafka_to_value didn't recursively convert to tuples, so they were of type Tuple[List[bytes], ...] instead of Tuple[Tuple[bytes, bytes], ...]
Migrated from D3806 (view on Phabricator)
kafka_to_value didn't recursively convert to tuples, so they were of type Tuple[List[bytes], ...] instead of Tuple[Tuple[bytes, bytes], ...]
Migrated from D3806 (view on Phabricator)