[jdk11u] RFR: 8286594: (zipfs) Mention paths with dot elements in ZipException and cleanups

[Christoph Langer]

The backport needed some resolving/adaptation to older zipfs code.
Method IndexNode:toString is not implemented, so this part of the upstream patch does not apply.

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Commit messages:
 - Backport 80cf9f3464c599fb7860432bf4ed506a3b298d8e

Changes: https://git.openjdk.java.net/jdk11u/pull/38/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u&pr=38&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286594
  Stats: 72 lines in 1 file changed: 31 ins; 38 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk11u/pull/38.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u pull/38/head:pull/38

PR: https://git.openjdk.java.net/jdk11u/pull/38