This covers changes to Vector, ArrayList, and PriorityQueue
collection constructors that both make them accommodate
traversals with different numbers of elements than reported
size(), and as a byproduct makes them fail less often with
concurrently modified non-concurrent ones.

It is common for academic papers investigating concurrency bugs in the JDK
to cite the classic

Collection c = new Vector();
// Mutate c in another thread
Vector v = new Vector(c); // may fail unexpectedly

Here the concurrency issue is not with "this", but with the
argument collection, which has unknown concurrency properties,

Because of this, synchronized Vector and unsynchronized ArrayList have the same issues.