RFR: 8311546: Certificate name constraints improperly validated with leading period [v2]

[Ben Perez]

> Updated the `constrains` method in `DNSName.java` to accept certificates with a leading period.

Ben Perez has updated the pull request incrementally with one additional commit since the last revision:

  Updated documentation, minor fixes in test

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16295/files
  - new: https://git.openjdk.org/jdk/pull/16295/files/cffa7b99..6db8c331

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16295&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16295&range=00-01

  Stats: 27 lines in 2 files changed: 1 ins; 18 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/16295.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16295/head:pull/16295

PR: https://git.openjdk.org/jdk/pull/16295