RFR: 8350542: Optional.orElseThrow(Supplier) does not specify behavior when supplier returns null

[simon]

Javadoc for java.util.Optional.orElseThrow(Supplier) misses mentioning of another possible cause of a NullPointerException - when the exception supplying function returns a null result.
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### Progress
- [ ] Change must be properly reviewed (1 review required, with at least 1 [Reviewer](https://openjdk.org/bylaws#reviewer))
- [x] Change requires CSR request [JDK-8354953](https://bugs.openjdk.org/browse/JDK-8354953) to be approved
- [x] Change must not contain extraneous whitespace
- [x] Commit message must refer to an issue

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Commit messages:
 - 8350542: fix extra trailing space.
 - 8350542: update orElseThrow JavaDoc from CSR specification.
 - 8350542: fix extra trailing space.
 - 8350542: Optional.orElseThrow(Supplier) does not specify behavior when supplier returns null

Changes: https://git.openjdk.org/jdk/pull/23905/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23905&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8350542
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23905.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23905/head:pull/23905

PR: https://git.openjdk.org/jdk/pull/23905