RFR: 8209038: Clarify the javadoc of Cipher.getParameters() [v5]

[Valerie Peng]

> Anyone can help review this javadoc update? The main change is the wording for the method javadoc of Cipher.getParameters()/CipherSpi.engineGetParameters(). The original wording is somewhat restrictive and request is to broaden this to accommodate more scenarios such as when null can be returned.
> The rest are minor things like add {@code } to class name and null, and remove redundant ".". 
> 
> Will file CSR after the review is close to being wrapped up.
> Thanks~

Valerie Peng 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 five additional commits since the last revision:

 - Merge branch 'master' of https://github.com/openjdk/jdk into JDK-8209038
 - update to address review feedback and minor javadoc cleanup
 - Update for getParameters()
 - Update w/ review feedbacks
 - 8209038: Clarify the javadoc of Cipher.getParameters()

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8117/files
  - new: https://git.openjdk.java.net/jdk/pull/8117/files/77e8fa0d..f9727edf

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8117&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8117&range=03-04

  Stats: 313143 lines in 4579 files changed: 242497 ins; 21053 del; 49593 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8117.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8117/head:pull/8117

PR: https://git.openjdk.java.net/jdk/pull/8117