<Swing Dev> RFR 8250853:Address reliance on default constructors in the javax.swing APIs

[Prasanta Sadhukhan]

Hi All,

Please review a fix for issue where it was seen that several classes 
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 public abstract classes for 
javax.swing module (as one part of overalll java.desktop change)

Bug: https://bugs.openjdk.java.net/browse/JDK-8250853

webrev: http://cr.openjdk.java.net/~psadhukhan/8250853/webrev.0/

CSR: https://bugs.openjdk.java.net/browse/JDK-8252021

Regards
Prasanta