RFR: 7008: Agent should properly support Class and Thread [v2]

[Marcus Hirt]

> Also fixes various issues and tests.

Marcus Hirt has updated the pull request incrementally with one additional commit since the last revision:

  Removing temporary workaround

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/192/files
  - new: https://git.openjdk.java.net/jmc/pull/192/files/9a2fc3f6..d48e1486

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=192&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=192&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.java.net/jmc/pull/192.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/192/head:pull/192

PR: https://git.openjdk.java.net/jmc/pull/192