[Play 2.6] i18n locale lookup behavior

It seems there is something wrong with the locale lookup behavior.

Expected Behavior

  1. application.conf is like below
play.i18n.langs = [ "ja", "ja-JP", "en", "en-US" ]
  1. access with Accept-Language: en-GB

  2. en is chosen for rendering

Actual Behavior

  1. default lang ja is chosen

This Actual Behavior does not satisfy RFC 4647 section 3.4.

I know how to fix it and I want to create a pull request.
Toward which branch should I create a pull request?

You should create pull requests against master, and request a backport.

The preferred language is specified through Langs.preferred:

Thank you very much. I will do that :grin: