RFR: 6201035: Undefined behavior of MatteBorder Ctors

[Prasanta Sadhukhan]

The behavior of MatteBorder constructors taking Insets object as a parameter is undocumented. It would throw NPE if null object is passed to it, which should be documented in the spec.

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

Commit messages:
 - 6201035: Undefined behavior of MatteBorder Ctors

Changes: https://git.openjdk.org/jdk/pull/10740/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10740&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-6201035
  Stats: 6 lines in 2 files changed: 6 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10740.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10740/head:pull/10740

PR: https://git.openjdk.org/jdk/pull/10740