Given the following document:

db.collection.insertOne({

  items: [

    {

      _id: ObjectId,

      name: 'foobar'

{{    }}}

  ]

});

Trying to `$unwind` the field path `$items.name` outputs nothing.

On the other hand, the output of this:

db.collection.aggregate([
  {
    $project: {
{{      type: { $type: '$items.name' }}}
{{    }}}
{{  }}}
]);

is the following:

{{{}}
  "_id" : ObjectId("..."),
  "type" : "array"
}

If the expression `$items.name` resolves to an array then why can I not `$unwind` this field path?