There is a special type of embedded object: the nested one. This resolves a problem related to Lucene indexing architecture, in which all the fields of embedded objects are viewed as a single object. During search, in Lucene, it is not possible to distinguish between values and different embedded objects in the same multi-valued array.
If we consider the previous order example, it's not possible to distinguish an item name and its quantity with the same query, as Lucene puts them in the same Lucene document object. We need to index them in different documents and then join them. This entire trip is managed by nested objects and nested queries.