[11u]: Backport of RFR 8211122: Reduce the number of internal classes made accessible to jdk.unsupported (and JDK-8205537 and JDK-8211121)

[Langer, Christoph]

Hi,

please help me reviewing the backport of "JDK-8211122: Reduce the number of internal classes made accessible to jdk.unsupported". The main reason for backporting this item is that it'll ease further backports which base on that changeset. The patch is quite extensive and hence doesn't fully apply. I had to resolve some rejects and also modify a few other places. Lots of the rejects were about copyright years (especially in the hotspot tests) which could be dropped. Find below the link for a full webrev and an incremental one which only contains my manual changes. I'm currently running it through SAP's test system to check for regressions.

Though this change is large and thorough review is tedious, I think the main issue is that we need 2 additional fixes to pull in before taking 8211122:
JDK-8205537: Drop of sun.applet package
JDK-8211121: Remove sun.reflect.ReflectionFactory::newInstanceForSerialization
As the names already suggest, both changes remove methods/classes. I'm not 100% sure whether these removals should be done in a JDK11 update releases. I rather think they could because the one is about Java applets which aren't supported with (Open-)JDK 11 anyway and the other removed method claims to only have been added in 9.0.0.4 to be used by the meanwhile removed CORBA modules (removed with JDK11). But I'd really like to have some opinions about these.

Here are the links:
Original bug: https://bugs.openjdk.java.net/browse/JDK-8211122
Original review discussion: https://mail.openjdk.java.net/pipermail/core-libs-dev/2018-November/056397.html
Original changeset: http://hg.openjdk.java.net/jdk/jdk/rev/3c6aa484536c
Full webrev: http://cr.openjdk.java.net/~clanger/webrevs/8211122.11u.full/
Incremental Webrev of manual changes: http://cr.openjdk.java.net/~clanger/webrevs/8211122.11u.manual/

Dependencies:
JDK-8205537 Bug: https://bugs.openjdk.java.net/browse/JDK-8205537
JDK-8205537 Changeset: http://hg.openjdk.java.net/jdk/jdk/rev/26a17d160081
JDK-8211121 Bug: https://bugs.openjdk.java.net/browse/JDK-8211121
JDK-8211121 Changeset: http://hg.openjdk.java.net/jdk/jdk/rev/f6e15aa9c16e

Thanks
Christoph