RFR: 8370467: BorderFactory.createBevelBorder and createSoftBevelBorder throws NPE for null highlight and shadow [v7]

[Prasanta Sadhukhan]

> If we pass null as highlight and shadow color to `BorderFactory.createBevelBorder` and `createSoftBevelBorder`
> it throws NPE which is not mentioned in the spec as the expected outcome.
> Fixed the NPE and the spec

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  javadoc update

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27949/files
  - new: https://git.openjdk.org/jdk/pull/27949/files/27ed5b21..f68195a6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27949&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27949&range=05-06

  Stats: 5 lines in 2 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/27949.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27949/head:pull/27949

PR: https://git.openjdk.org/jdk/pull/27949