RFR: 8257769: Cipher.getParameters() throws NPE for ChaCha20-Poly1305 [v4]

[Jamil Nimeh]

> This fix corrects a problem where ChaCha20-Poly1305 objects prior to init throw NPE when getParameters() is called.  It will now generate parameters containing a random nonce on each pre-init call to getParameters(). Post-initialization calls to the getParameters() method will always return the same set of parameters until the next initialization occurs.

Jamil Nimeh has updated the pull request incrementally with one additional commit since the last revision:

  Simplfied getNonceFromParams to use IvParameterSpec.getIV()

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1644/files
  - new: https://git.openjdk.java.net/jdk/pull/1644/files/0f74545b..fc2cb52f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1644&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1644&range=02-03

  Stats: 26 lines in 1 file changed: 1 ins; 23 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1644.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1644/head:pull/1644

PR: https://git.openjdk.java.net/jdk/pull/1644