RFR: 8342700: Set the default value of DirectCodeBuilder::handlers to Null [v2]

[Shaojin Wen]

> Set the default value of DirectCodeBuilder::handlers to Null to reduce overhead in scenarios where there is no handler.

Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:

  List.of

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21598/files
  - new: https://git.openjdk.org/jdk/pull/21598/files/a4ef57af..f9114bd0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21598&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21598&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21598.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21598/head:pull/21598

PR: https://git.openjdk.org/jdk/pull/21598