RFR: 8266220: keytool still prompt for store password on a password-less pkcs12 file if -storetype pkcs12 is specified

[Weijun Wang]

It's awkward that for a password-less pkcs12 keystore, `keytool -list` does not prompt for a password but `keytool -list -storetype pkcs12` does.

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

Commit messages:
 - 8266220: keytool still prompt for store password on a password-less pkcs12 file if -storetype pkcs12 is specified

Changes: https://git.openjdk.java.net/jdk/pull/3764/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3764&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266220
  Stats: 35 lines in 2 files changed: 27 ins; 2 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3764.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3764/head:pull/3764

PR: https://git.openjdk.java.net/jdk/pull/3764