Here's the starting point for openjdk contributing: http://openjdk.java.net/contribute/
Here's your post in the mail archives :http://mail.openjdk.java.net/pipermail/serviceability-dev/2018-July/024441.html
Most people will post a webrev to cr.openjdk.java.net for larger changesets. Most attachments are stripped when sent to the mailing list.
