RFR: 8344892: beans/finder/MethodFinder.findMethod incorrectly returns null [v2]

[Alexander Zvegintsev]

> During the [JDK-8344891 Remove uses of sun.misc.ReflectUtil in java.desktop](https://bugs.openjdk.org/browse/JDK-8344891) it was discovered that `beans/finder/MethodFinder.findMethod' incorrectly returned null if a signature was not in the cache and added it to the cache if it was already there:
> 
> 
> Method method = CACHE.get(signature);
> return (method == null) ? method : CACHE.create(signature);
> 
> This resulted in a [significant drop in performance](https://bugs.openjdk.org/browse/JDK-8350573).
> 
> ----
> 
> Before ReflectUtil was removed, it worked by coincidence:
> 
> 
> Method method = CACHE.get(signature);
> return (method == null) || isPackageAccessible(method.getDeclaringClass()) ? method : CACHE.create(signature);
> 
> 
> 
> 
> 1. `Cache#get` non-obviously creates a value in Cache, this in turn allowed us to avoid the NPE in the `(method == null) || isPackageAccessible(method.getDeclaringClass())` condition
> 
> 
> https://github.com/openjdk/jdk/blob/d6c4be672f6348f8ed985416ed90d0447f5d5bb3/src/java.desktop/share/classes/com/sun/beans/util/Cache.java#L120-L126
> 
> 2. `isPackageAccessible(method.getDeclaringClass())` was evaluated as true
> 
> This is how we previously returned the cached value.
> 
> ---
> 
> So the solution is obvious:
> 
> 
> Method method = CACHE.get(signature);
> return (method != null) ? method : CACHE.create(signature);
> 
> 
> Testing is green.

Alexander Zvegintsev has updated the pull request incrementally with one additional commit since the last revision:

  return CACHE.get(signature);

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/23845/files
  - new: https://git.openjdk.org/jdk/pull/23845/files/36546eb6..e6f0f433

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23845&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23845&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23845.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23845/head:pull/23845

PR: https://git.openjdk.org/jdk/pull/23845