RFR: 8284105: Update security libraries to use sealed classes [v2]

[Sean Mullan]

> Please review these changes to update the security libraries to use sealed classes. See JEP 409 for more details on sealed classes.
> 
> No CSR is required as all the changes are to internal classes. A few classes that did not have subclasses were simply marked final instead of sealed.

Sean Mullan has updated the pull request incrementally with one additional commit since the last revision:

  Make some classes package-private instead of sealed.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8165/files
  - new: https://git.openjdk.java.net/jdk/pull/8165/files/52aa0ad6..c27b1ba0

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8165&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8165&range=00-01

  Stats: 93 lines in 8 files changed: 42 ins; 38 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8165.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8165/head:pull/8165

PR: https://git.openjdk.java.net/jdk/pull/8165