Elasticsearch version: 6.0.0

Plugins installed: ec2-discovery

Description of the problem including expected versus actual behavior:

ec2 service endpoint to connect to. This will be automatically figured out by the ec2 client based on the instance location, but can be specified explicitly
The document states ec2 service endpoint is automatically figured out by ec2 client, but I need to set the endpoint to make the plugin work.

This document is correct if the plugin uses AmazonEC2ClientBuilder to build AmazonEC2Client instance. But AmazonEC2Client is created directly, so the endpoint is set to default endpoint, "https://ec2.us-east-1.amazonaws.com."

Related #25619