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

[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).

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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.

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Commit messages:
 - 8344892: beans/finder/MethodFinder.findMethod incorrectly returns null

Changes: https://git.openjdk.org/jdk/pull/23845/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23845&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344892
  Stats: 1 line in 1 file changed: 0 ins; 0 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