Make sun.net.www.MessageHeader final, and remove
`@SuppressWarnings("this-escape")`
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Commit messages:
- fix
Changes: https://git.openjdk.org/jdk/pull/18060/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18060&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8325361
Stats: 6 lines in 1 file changed: 0 ins; 2 del; 4 mod
Patch: https://git.openjdk.org/jdk/pull/18060.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/18060/head:pull/18060
PR: https://git.openjdk.org/jdk/pull/18060
