Specifies the read concern. Only compatible with a write stage. (e.g. $out, $merge)
Aggregate commands do not support the ReadConcern.Level.linearizable level.
See Implementation
https://github.com/mongodb/specifications/blob/7745234f93039a83ae42589a6c0cdbefcffa32fa/source/read-write-concern/read-write-concern.rst
Specifies the read concern. Only compatible with a write stage. (e.g. $out, $merge)
Aggregate commands do not support the ReadConcern.Level.linearizable level.