RFR: 8269130: Replace usages of Collection.toArray() with Collection.toArray(T[]) to avoid redundant array copying

[Michael Bien]

On Mon, 14 Jun 2021 17:00:29 GMT, Andrey Turbanov <github.com+741251+turbanoff at openjdk.org> wrote:

> I found few places, where code initially perform `Object[] Colleciton.toArray()` call and then manually copy array into another array with required type.
> This PR cleanups such places to more shorter call `T[] Collection.toArray(T[])`.

src/java.base/share/classes/java/security/Security.java line 656:

> 654:             return null;
> 655: 
> 656:         return candidates.toArray(new Provider[0]);

`candidates.toArray(new Provider[candidates.size()]);`

would use the fast path of the toArray() implementation. Performance probably doesn't matter much in a lot of this cases, but since its only a few characters more, its still worth considering IMO.

The only places I would leave this out are on the HashTable and on the Vector collections in this PR, since calling one synchronized method is not the same as calling two - concurrency wise.

(i am no reviewer)

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PR: https://git.openjdk.java.net/jdk/pull/4487