This PR suggests introducing an internal class in `java.base` to simplify the use of some `MethodHandles.Lookup` operations.
While the utility of the methods might appear to be limited in classes with many static `VarHandle`/`MethodHandle` variables, it should be noted that the class files become smaller and simpler. Here are some examples: | Class File | Base [Bytes] | Patch [Byte] | | --------------------------------| ------------- | ------------ | | FutureTask.class | 10255 | 10154 | | AtomicBoolean.class | 5364 | 5161 | |AtomicMarkableReference.class | 3890 | 3687 |  The new `MethodHandlesInternal.class` file is of size 2012 bytes. In total for `java.base` we have: | Build map "jdk" | Size [Bytes] | | ---------------| ------------- | | Base | 5963657 | | Patch | 5962751 | | Delta | 906| For 60 billion instances, this represents 54 TB. ------------- Commit messages: - Fix copyright headers - Introduce MethodHandlesInternal Changes: https://git.openjdk.org/jdk/pull/20972/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20972&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8325949 Stats: 423 lines in 31 files changed: 109 ins; 202 del; 112 mod Patch: https://git.openjdk.org/jdk/pull/20972.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/20972/head:pull/20972 PR: https://git.openjdk.org/jdk/pull/20972
