RFR: 8209003: Consolidate use of empty collections in java.lang.module

[mandy chung]

This cleanup looks fine.

Mandy

On 8/7/18 9:16 AM, Claes Redestad wrote:
> Hi,
> 
> feel free to review this cleanup to consolidate some uses of 
> Collections.empty/unmodifiableXx.. to Set/Map/List.of()/copyOf(), as 
> appropriate. This aligns better with code already generated by jlink, so 
> avoids observing a mix of many implementation classes in some places..
> 
> Webrev: http://cr.openjdk.java.net/~redestad/8209003/jdk.00/
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8209003
> 
> Due the specified need to throw IAE rather than NPE in certain cases, 
> code in some performance-insensitive API methods in 
> ModuleDescriptor.Builder now does an extra copy up front 
> (List/Set/Map.copyOf will throw NPE on any null element or key). I'd 
> rather keep the code simple than add extra handling to squeeze out the 
> last bit of performance here (maybe I'm getting old...)
> 
> Thanks!
> 
> /Claes
>