Amazon Elasticsearch Service now supports open source Elasticsearch 6.7 and Kibana 6.7. The new version of Elasticsearch and Kibana offers several new features and improvements, including BKD backed geo-shapes datatype, median absolute deviation aggregation, and support for nested fields in composite aggregations

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/06/amazon-elasticsearch-service-announces-support-for-elasticsearch-67/