PriorityQueue(collection) should throw NPE

[Martin Buchholz]

This is a bug report with fix.
(Chris, please file a bug)

Summary: PriorityQueue(collection) should throw NPE if collection
contains a null

Description:
PriorityQueue spec says:

"A priority queue does not permit {@code null} elements."

but the constructor taking a collection does not enforce that.

Fix:
http://cr.openjdk.java.net/~martin/webrevs/openjdk7/PriorityQueueConstructor/

Martin