Updated `ListFormat` custom pattern parsing to avoid regex matching. The implementation now locates placeholders and delimiters with literal string operations.
Added coverage for invalid long custom patterns and for regex metacharacters in custom patterns, which should be treated as literals. --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - Regex metachar tests - replaced String.split() - initial commit Changes: https://git.openjdk.org/jdk/pull/31343/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=31343&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8385736 Stats: 163 lines in 2 files changed: 111 ins; 8 del; 44 mod Patch: https://git.openjdk.org/jdk/pull/31343.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/31343/head:pull/31343 PR: https://git.openjdk.org/jdk/pull/31343
