Test that newly-added Java 8 ALPN works

In https://bugs.java.com/bugdatabase/view_bug.do?bug_id=8230977 Java 8 received a backport of the Java 9 ALPN API. It appears to be available starting in 8u251 or u252. Support was added to Netty in https://github.com/netty/netty/pull/10196 and released in 4.1.49.

Since we do some of our own detection, we should make sure it works with these more recent Java 8 versions. Even though Java 8 has very poor AES GCM performance, if it is an additional option it can help users on nicher platforms why may not need high throughput. We will also need to update SECURITY.md.

It may make sense to split out a separate issue for OkHttp.

まず、既存の Java ALPN 検出と SECURITY.md の場所を確認し、次に Java 8u251/8u252 と Netty 4.1.49 で導入された動作を比較します。新しい Java 8 ALPN API が検出されることを確認するカバレッジを追加し、必要に応じて SECURITY.md を更新してください。テストはサポート対象の Java バージョンで成功する必要があります。

索引モデルが issue の本文から書いたものです。