RFR: 8114830: (fs) Files.copy fails due to interference from something else changing the file system [v6]

[Brian Burkhalter]

> Throw a `FileSystemException` if attempting to create the target file with `O_EXCL` fails with `EEXIST`.

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

  8114830: Minor CopyTask cleanup

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15141/files
  - new: https://git.openjdk.org/jdk/pull/15141/files/541f36b2..f9440366

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15141&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15141&range=04-05

  Stats: 6 lines in 1 file changed: 2 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/15141.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15141/head:pull/15141

PR: https://git.openjdk.org/jdk/pull/15141