RFR: 8309841: Jarsigner should print a warning if an entry is removed [v7]

[Weijun Wang]

> There ~are two~ is one change~s~:
> 
> 1. In `jarsigner -verify`, check a .SF file contains un-existing entries and print them out as
> 
> Warning: nonexistent signed entries detected: [a]
> 
> ~2. In `JarSigner::sign0`, when creating a new .SF file, only include signed file entries.~
> 
> *Update*: Even when the JAR file is re-signed, the hash entry for the missing file will be in the new .SF file. There is no way to tell if this is for a file entry or a user-defined entry.

Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:

  more testcases in JarUtilsTest.java

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/19599/files
  - new: https://git.openjdk.org/jdk/pull/19599/files/097b99cb..7ad36e10

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19599&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19599&range=05-06

  Stats: 18 lines in 1 file changed: 11 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/19599.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19599/head:pull/19599

PR: https://git.openjdk.org/jdk/pull/19599