RFR: 8324210: Serial: Remove unused methods in Generation [v2]

[Albert Mingkun Yang]

> Trivial removing dead code.

Albert Mingkun Yang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - review
 - Merge branch 'master' into trivial
 - trivial

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17497/files
  - new: https://git.openjdk.org/jdk/pull/17497/files/300f5c56..4305f2f7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17497&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17497&range=00-01

  Stats: 860 lines in 58 files changed: 560 ins; 143 del; 157 mod
  Patch: https://git.openjdk.org/jdk/pull/17497.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17497/head:pull/17497

PR: https://git.openjdk.org/jdk/pull/17497