RFR: 8345249: Apply some conservative cleanups in FileURLConnection [v2]

[Daniel Jeliński]

On Sat, 30 Nov 2024 18:39:01 GMT, Eirik Bjørsnøs <eirbjo at openjdk.org> wrote:

>> Please review this PR which applies various cleanups to `sun.net.www.protocol.file.FileURLConnection`.
>> 
>> This class is known to be an _old, intricate, and hard to maintain piece of code._  However, there are some relatively straightforward and safe cleanups possible which improve readability and makes it easier to reason about what's going on in this class.
>> 
>> In this PR, I have chosen to make each individual small change a separate commit. This to assist review of each individual change, which can otherwise disappear a bit when reviewing the PR as a whole. 
>> 
>> A detailed listing of each commit follows in a separate comment.
>> 
>> This is a pure cleanup PR, no tests are added or updated in this PR.
>
> Eirik Bjørsnøs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Replace String::valueOf with Long::toString

Marked as reviewed by djelinski (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/22459#pullrequestreview-2567282512