Spec and API review for {Int,Long,Double}SummaryStatistics

[Brian Goetz]

I've posted a survey at:
   https://www.surveymonkey.com/s/5VTLT26

To do an API and spec review for the classes 
Int/Long/DoubleSummaryStatistics.  If you have comments, please provide 
them in the SurveyMonkey form.  Usual password.