RFR: 8292955: Collections.checkedMap Map.merge does not properly check key and value [v2]

[Korov]

> When the specified key did not associated with a value, should check the `key` and `value` type.

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

  modify the code based on the review

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/18141/files
  - new: https://git.openjdk.org/jdk/pull/18141/files/aac03cfc..14827cf3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18141&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18141&range=00-01

  Stats: 6 lines in 1 file changed: 6 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18141.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18141/head:pull/18141

PR: https://git.openjdk.org/jdk/pull/18141