Elasticsearch has two interesting features mapping wise

• nested objects https://www.elastic.co/guide/en/elasticsearch/guide/current/nested-objects.html
• parent child https://www.elastic.co/guide/en/elasticsearch/guide/current/parent-child.html

We should offer the option for a user to chose when an @IndexedEmbedded is mapped as manual denormalization, nested object or parent child.

We can orthogonally add support for this in the Lucene backend.