RFR: 8262186: Callback semantics of the method X509KeyManager.chooseClientAlias(...)

[Weijun Wang]

This code change collects all key types and runs `chooseClientAlias` only once.

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Commit messages:
 - no more reflection in test
 - 8262186: Callback semantics of the method X509KeyManager.chooseClientAlias(...)

Changes: https://git.openjdk.java.net/jdk/pull/5257/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5257&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262186
  Stats: 427 lines in 4 files changed: 396 ins; 20 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5257.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5257/head:pull/5257

PR: https://git.openjdk.java.net/jdk/pull/5257