[jdk21u-dev] RFR: 8335638: Calling VarHandle.{access-mode} methods reflectively throws wrong exception

[Rui Li]

A clean backport for https://bugs.openjdk.org/browse/JDK-8335638.

According to [the API specification](https://github.com/openjdk/jdk/blob/d7b941640638b35f9ac1ef11cd6bf6ccb795c29a/src/java.base/share/classes/java/lang/invoke/VarHandle.java#L435-L442), invoking VarHandle.{access-mode} methods reflectively throws an `UnsupportedOperationException`. However, it currently throws exception is an `UnsatisfiedLinkError` instead. (Pretty much what's in the `Problem` section of the [CSR](https://bugs.openjdk.org/browse/JDK-8335805))

Low risk. See Hannes Greule's comment in CSR: https://bugs.openjdk.org/browse/JDK-8335805:

>  it only applies when invoking those methods reflectively - doing that always results in some form of Throwable being thrown - MethodHandle already throws UnsupportedOperationException in the same case - The exception is wrapped by an InvocationTargetException


Note: I'm not sure if there are any additional processes aside from a pr itself when backporting a fix requiring a CSR to previous versions. Let me know if it requires something else.

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Commit messages:
 - Backport 9fe6e2316aef8fd125a7905cff2a2d9ae5d26109

Changes: https://git.openjdk.org/jdk21u-dev/pull/2144/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2144&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335638
  Stats: 77 lines in 2 files changed: 72 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2144.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2144/head:pull/2144

PR: https://git.openjdk.org/jdk21u-dev/pull/2144