<Swing Dev> RFR: 8252722: More Swing plaf APIs that rely on default constructors [v3]

[Prasanta Sadhukhan]

> Please review a fix for issue where it was seen that several classes in plaf package rely on default constructors as
> part of their public API.
> It's to be noted that "A no-arg public constructor is generated by the compiler for a class if it does not declare an
> explicit constructor. While convenient, this is inappropriate for many kinds of formal classes, both because the
> constructor will have no javadoc and because the constructor may be unintended."
> 
> For the JDK, classes intended to be used outside of the JDK, public classes in exported packages, should not rely on
> default constructors.
> 
> Proposed fix is to add explicit public no-arg constructors for public classes and protected no-arg constructor for
> protected classes for javax.swing module

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

  Address review comments

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/251/files
  - new: https://git.openjdk.java.net/jdk/pull/251/files/38ff7128..7cdc06c4

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=251&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=251&range=01-02

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/251.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/251/head:pull/251

PR: https://git.openjdk.java.net/jdk/pull/251