8325730: StringBuilder.toString allocation for the empty String

[shipilev]

Clean backport to resolve the regression introduced in JDK 19.

Additional testing:

• Linux x86_64 server fastdebug, all

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8325730 needs maintainer approval

Issue

• JDK-8325730: StringBuilder.toString allocation for the empty String (Bug - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk21u-dev.git pull/364/head:pull/364
$ git checkout pull/364

Update a local copy of the PR:
$ git checkout pull/364
$ git pull https://git.openjdk.org/jdk21u-dev.git pull/364/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 364

View PR using the GUI difftool:
$ git pr show -t 364

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk21u-dev/pull/364.diff

Webrev

Link to Webrev Comment

[bridgekeeper]

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[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

⚠️ @shipilev This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 01: Full - Incremental (8393e8f6)
• 00: Full (0f183405)

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[bridgekeeper]

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