RFR: 8252399: Update mapMulti documentation to use type test pattern instead of instanceof once JEP 375 exits preview [v9]

[Patrick Concannon]

> Hi,
> 
> Could someone please review my changeset for JDK-8252399: 'Update mapMulti documentation to use type test pattern instead of instanceof once JEP 375 exits preview' ?
> 
> This change updates the example code displayed in the API documentation for mapMulti to use the type test pattern introduced in [JEP375](https://openjdk.java.net/jeps/375).
> 
> Kind regards,
> Patrick

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

  8252399: Added note for keeping example in sync with test; updated example to use real values

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2544/files
  - new: https://git.openjdk.java.net/jdk/pull/2544/files/c47fbf92..944c7d5e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2544&range=08
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2544&range=07-08

  Stats: 9 lines in 2 files changed: 2 ins; 5 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2544.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2544/head:pull/2544

PR: https://git.openjdk.java.net/jdk/pull/2544