RFR: 6227536: KeyGenerator.init() methods do not throw IllegalArgumentException for keysize == 0 [v4]

[Kevin Driver]

> As mentioned in the bug report, this issue *should not* be a framework-level issue, since potentially an individual provider could create a keysize of zero to have a certain significance. 
> 
> In the changes made here, the check is for `keysize <= 0` and this message indicates this is a check characteristic to the `SunJCE` provider.

Kevin Driver has updated the pull request incrementally with one additional commit since the last revision:

  remove provider mention

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9679/files
  - new: https://git.openjdk.org/jdk/pull/9679/files/2cf5b7bf..3a7367e8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9679&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9679&range=02-03

  Stats: 4 lines in 2 files changed: 0 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/9679.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9679/head:pull/9679

PR: https://git.openjdk.org/jdk/pull/9679