RFR: 8158689: java.security.KeyPair should implement Destroyable

[Anthony Scarpino]

Hi,

I need a review of this change.  It makes KeyPair implement Destroyable and implements the methods to call the underlying privateKey.  It also sets the public and private key to 'final'.

The bug includes a CSR and Release Notes
CSR: https://bugs.openjdk.java.net/browse/JDK-8275823
RN: https://bugs.openjdk.java.net/browse/JDK-8275826

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Commit messages:
 - initial fix

Changes: https://git.openjdk.java.net/jdk/pull/6089/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6089&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8158689
  Stats: 62 lines in 2 files changed: 55 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6089.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6089/head:pull/6089

PR: https://git.openjdk.java.net/jdk/pull/6089