[8] Review request for 8013571: TreeModelEvent doesn't accept " null " for root as Javadoc specifies.

[sergey malenkov]

Hello,

Could you please review the following fix:
fix: http://cr.openjdk.java.net/~malenkov/8013571.8.0 
<http://cr.openjdk.java.net/%7Emalenkov/8013571.8.0/>
bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8013571
The behavior fixed according to JavaDoc.

Thanks,
SAM