RFR: JDK-8319626: Override toString() for ZipFile [v2]

[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_).
> 
> This change is primarily to provide a more informative String representation of the two classes rather than the default hexadecimal representation of the hash code.

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

  reflect review: change string value and drop spec

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16643/files
  - new: https://git.openjdk.org/jdk/pull/16643/files/bc3cf3e1..c75029cb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16643&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16643&range=00-01

  Stats: 6 lines in 1 file changed: 0 ins; 5 del; 1 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