Initial webrev with changes for JDK 9

[Mandy Chung]

> On Mar 16, 2016, at 11:50 AM, Mandy Chung <mandy.chung at oracle.com> wrote:
> 
>> On Mar 16, 2016, at 10:30 AM, Peter Levart <peter.levart at gmail.com> wrote:
>> 
>> In java.lang.ClassLoader:
>> 
>> ...the package-private definePackage(String name, Module m) is OK to use a single packages.compute(...) call performance-wise since it is pre-screened with packages.get() in public getDefinedPackage(String name) method.

Peter - thanks for clarifying this.  This suggests no need to change definePackage(String,Module).

>> But there's also a package-private packages() method (a basis for public methods getPackages() and getDefinedPackages()) that constructs a Stream<Package> of defined Packages which unnecessarily calls definePackage() for each value of packages map:
>> 
>>   Stream<Package> packages() {
>>       return packages.values().stream()
>>                      .map(p -> definePackage(p.packageName(), p.module()));
>>   }
>> 
>> 
>> It would be nice performance-wise to avoid calling definePackage if the value is already a Package:
>> 
>>   Stream<Package> packages() {
>>       return packages.values().stream()
>>                      .map(p -> p instanceof Package
>>                                ? (Package) p
>>                                : definePackage(p.packageName(), p.module()));
>>   }
>> 

I have cleaned up the code to use toPackage instead:
  http://cr.openjdk.java.net/~mchung/jigsaw/webrevs/jigsaw-m3/webrev-03-16/index.html

Mandy