RFR: 6201035: Document NPE for passing null insets to constructors and methods of several javax.swing.border.* classes [v6]

[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:

  TitledBorder added

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10740/files
  - new: https://git.openjdk.org/jdk/pull/10740/files/e7081b0d..40891ee7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10740&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10740&range=04-05

  Stats: 2 lines in 1 file changed: 2 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