RFR: JDK-8319626: Override toString() for ZipFile [v7]

[Justin Lu]

> Please review this PR and [CSR](https://bugs.openjdk.org/browse/JDK-8319982) which overrides and provides an implementation of `toString()` in _java.util.zip.ZipFile_ (and by extension, _java.util.jar.JarFile_).

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  drop additional specification

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/16643/files
  - new: https://git.openjdk.org/jdk/pull/16643/files/21762cd2..159c4c8f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16643&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16643&range=05-06

  Stats: 4 lines in 1 file changed: 0 ins; 4 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16643.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16643/head:pull/16643

PR: https://git.openjdk.org/jdk/pull/16643