[jdk13u-dev] RFR: 8196969: JTreg Failure: serviceability/sa/ClhsdbJstack.java causes NPE

[Ekaterina Vergizova]

I'd like to backport 8196969 to 13u for parity with 11u.
The patch applies cleanly.
Tested with tier1; new test fails without the patch, passes with it.

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Commit messages:
 - Backport c4f5c4fe9ba9c7ee9f46da309d8bff4ecf771f49

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/113/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=113&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8196969
  Stats: 181 lines in 3 files changed: 180 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/113.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/113/head:pull/113

PR: https://git.openjdk.java.net/jdk13u-dev/pull/113