RFR: 7357: Double-Checked Locking in Agent Plugin code [v2]

[Guru Hb]

> Trivial Fortify warning fix

Guru Hb has updated the pull request incrementally with one additional commit since the last revision:

  Fixing formatting error

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/282/files
  - new: https://git.openjdk.java.net/jmc/pull/282/files/e48a53ae..c9488a1d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=282&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=282&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jmc/pull/282.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/282/head:pull/282

PR: https://git.openjdk.java.net/jmc/pull/282