RFR: 8330815: Use pattern matching for instanceof in KeepAliveCache [v2]

[Christoph Langer]

> In su.net.www.http.KeepAliveCache we could use pattern matching for instanceof.

Christoph Langer has updated the pull request incrementally with one additional commit since the last revision:

  Add Daniel's more awesome suggestion

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18885/files
  - new: https://git.openjdk.org/jdk/pull/18885/files/a7129acd..5c9f5cc9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18885&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18885&range=00-01

  Stats: 7 lines in 1 file changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/18885.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18885/head:pull/18885

PR: https://git.openjdk.org/jdk/pull/18885