RFR: 8299835: (jrtfs) Unnecessary null check in JrtPath.getAttributes

[Andrey Turbanov]

`jdk.internal.jrtfs.JrtFileSystem#getFileAttributes` never return `null`

https://github.com/openjdk/jdk/blob/679e485838881c1364845072af305fb60d95e60a/src/java.base/share/classes/jdk/internal/jrtfs/JrtFileSystem.java#L206-L213
So, no need to check for `null` its result.
Seems it was copied from ZipPath (name of variable suggests that) - https://github.com/openjdk/jdk/blob/master/src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipPath.java#L769. But for ZipFileSystem `null` is expected.

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Commit messages:
 - [PATCH] Unnecessary null check in JrtPath.getAttributes

Changes: https://git.openjdk.org/jdk/pull/11911/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11911&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299835
  Stats: 5 lines in 1 file changed: 0 ins; 4 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/11911.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11911/head:pull/11911

PR: https://git.openjdk.org/jdk/pull/11911