RFR: 8293886: The abstract keyword can be removed in AESCipher [v2]

[Xue-Lei Andrew Fan]

> Hi,
> 
> Please review this simple fix for readability.
> 
> In the AES cipher implementation, the AESCipher class is defined as abstract.  As is not necessary as there is no abstract method in this class. Code reader may try to search for abstract methods if the abstract keyword is present.
> 
> BTW, I also added Override tags and make a few other cleanup, for example adding the 'final' keywords.
> 
> Thanks,
> Xuelei

Xue-Lei Andrew Fan has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - remove unused import
 - Merge
 - update copyright year
 - 8293886: The abstract keyword can be removed in AESCipher

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10297/files
  - new: https://git.openjdk.org/jdk/pull/10297/files/defa6e5d..350bbe1b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10297&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10297&range=00-01

  Stats: 277903 lines in 3883 files changed: 143337 ins; 88425 del; 46141 mod
  Patch: https://git.openjdk.org/jdk/pull/10297.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10297/head:pull/10297

PR: https://git.openjdk.org/jdk/pull/10297