RFR: 8299864: ZipFileStore#supportsFileAttributeView(String) doesn't throw NPE [v3]

[Per Minborg]

> This PR proposes to add null-checking for some parameter arguments in `ZipFileStore`.

Per Minborg has updated the pull request incrementally with one additional commit since the last revision:

  Add test method comment

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11926/files
  - new: https://git.openjdk.org/jdk/pull/11926/files/8c465592..84813af1

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11926&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11926&range=01-02

  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11926.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11926/head:pull/11926

PR: https://git.openjdk.org/jdk/pull/11926