RFR: JDK-8315042 NPE in PKCS7.parseOldSignedData [v6]

[Mark Powers]

> https://bugs.openjdk.org/browse/JDK-8315042

Mark Powers has updated the pull request incrementally with one additional commit since the last revision:

  improved @summary

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15844/files
  - new: https://git.openjdk.org/jdk/pull/15844/files/2fe7e47c..5def33dc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15844&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15844&range=04-05

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15844.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15844/head:pull/15844

PR: https://git.openjdk.org/jdk/pull/15844