[11u] RFR: 8254631: Better support ALPN byte wire values in SunJSSE

[Doerr, Martin]

Hi,

JDK-8254631 is backported to 11.0.12-oracle. I'd like to backport it for parity.
It applies cleanly, but the javadoc parts don't compile with 11u. They are not compatible with 11u and are documented to be dropped in the CSR (linked below).
As also documented in the CSR, the old behavior can get restored by specifying the property: jdk.tls.alpnCharset=UTF-8

Bug:
https://bugs.openjdk.java.net/browse/JDK-8254631

Original change:
https://git.openjdk.java.net/jdk/commit/fe5cccc1

11u CSR:
https://bugs.openjdk.java.net/browse/JDK-8264177

11u backport:
http://cr.openjdk.java.net/~mdoerr/8254631_ALPN_11u/webrev.00/

Please review.

Best regards,
Martin