[jdk11u-dev] RFR: 8208249: TriggerUnloadingByFillingMetaspace generates garbage class names

[Goetz Lindenmaier]

I backport this for parity with 11.0.16-oracle.

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Commit messages:
 - Backport 3d94ce71b5c379627406b3c889058d49bd5b7622

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/858/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=858&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8208249
  Stats: 8 lines in 1 file changed: 6 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/858.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/858/head:pull/858

PR: https://git.openjdk.java.net/jdk11u-dev/pull/858