Improve the speed of Method.hashCode by caching the hashcode on first use. I've seen an application where Method.hashCode is a hot path, and this is a fairly simple speedup. The memory overhead is low.
This addresses issue [JDK-8332249](https://bugs.openjdk.org/browse/JDK-8332249). Before: Benchmark Mode Cnt Score Error Units # Intel Skylake MethodHashCode.benchmarkHashCode avgt 5 1.843 ± 0.149 ns/op # Arm Neoverse N1 MethodHashCode.benchmarkHashCode avgt 5 2.363 ± 0.091 ns/op After: Benchmark Mode Cnt Score Error Units # Intel Skylake MethodHashCode.benchmarkHashCode avgt 5 1.121 ± 1.189 ns/op # Arm Neoverse N1 MethodHashCode.benchmarkHashCode avgt 5 1.001 ± 0.001 ns/op ------------- Commit messages: - Remove changes to JavaDoc per guidance. - Fix whitespace issues pointed by the bot - Micro-optimize Method.hashCode Changes: https://git.openjdk.org/jdk/pull/19433/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19433&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8332249 Stats: 58 lines in 2 files changed: 57 ins; 0 del; 1 mod Patch: https://git.openjdk.org/jdk/pull/19433.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/19433/head:pull/19433 PR: https://git.openjdk.org/jdk/pull/19433
