RFR: 6201035: Document NPE for passing null insets to constructors and methods of several Border classes [v5]

[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.

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

  Rectify javadoc of more border classes/methods

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10740/files
  - new: https://git.openjdk.org/jdk/pull/10740/files/391bf7f3..e7081b0d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10740&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10740&range=03-04

  Stats: 22 lines in 9 files changed: 12 ins; 0 del; 10 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