RFR: 8057113: (fs) Path should have a method to obtain the filename extension [v19]

[Roger Riggs]

On Fri, 14 Oct 2022 16:38:54 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Resurrection of the proposal to add a method to obtain the filename extension originated in PR [2319](https://github.com/openjdk/jdk/pull/2319).
>
> Brian Burkhalter has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 24 additional commits since the last revision:
> 
>  - 8057113: Revise specification and align default implementation and test with it
>  - Merge
>  - 8057113: Remove API note
>  - 8057113: Change specification as suggested in review
>  - 8057113: Update specification, implementation, and test
>  - 8057113: Correct length 2 case; update test cases
>  - 8057113: Revert return type back to a nullable-String; update test
>  - Merge
>  - 8057113: Remove extensions() test method; add threthree new test cases
>  - 8057113: Revert excision of wild cards from imports
>  - ... and 14 more: https://git.openjdk.org/jdk/compare/2398d46b...104a7116

The new spec for determining the extension looks fine.

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Marked as reviewed by rriggs (Reviewer).

PR: https://git.openjdk.org/jdk/pull/8066