RFR: 8255348: NPE in PKIXCertPathValidator event logging code [v2]

[Sean Coffey]

> Correction of NPE and updating of test cases. Minor refactoring of test library also.

Sean Coffey has updated the pull request incrementally with one additional commit since the last revision:

  Sean Mullan review update

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2150/files
  - new: https://git.openjdk.java.net/jdk/pull/2150/files/a59dd592..8a344a85

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2150&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2150&range=00-01

  Stats: 10 lines in 1 file changed: 0 ins; 7 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2150.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2150/head:pull/2150

PR: https://git.openjdk.java.net/jdk/pull/2150