We do this for fields that are not named "created_at" and "updated_at", I don't know if other fields need to be ignored as well. I also don't know why the properties are inside another "properties" and not just outside it, would probably be easier to upgrade and to deal with...
Since Elasticsearch 2.x fields cannot be referenced by short name: https://www.elastic.co/guide/en/elasticsearch/reference/current/breaking_20_mapping_changes.html#_fields_cannot_be_referenced_by_short_name
So for example in a document like this
we must use "properties.age" in queries.
We do this for fields that are not named "created_at" and "updated_at", I don't know if other fields need to be ignored as well. I also don't know why the properties are inside another "properties" and not just outside it, would probably be easier to upgrade and to deal with...
/cc @bcardiff @nekron