java -version:
openjdk version "25.0.4.1" 2026-08-18 LTS
OpenJDK Runtime Environment Temurin-25.0.4.1+1 (build 25.0.4.1+1-LTS)
OpenJDK 64-Bit Server VM Temurin-25.0.4.1+1 (build 25.0.4.1+1-LTS, mixed mode, sharing)

-- without -Djdk.tracePinnedThreads=full --
java.version=25.0.4.1
jdk.tracePinnedThreads=null
Running a virtual thread that holds a monitor across Thread.sleep(200)...
Done. If jdk.tracePinnedThreads still worked on this JDK, a pinned-thread stack trace would have printed above while the virtual thread was inside doWorkHoldingMonitor.

-- with -Djdk.tracePinnedThreads=full --
java.version=25.0.4.1
jdk.tracePinnedThreads=full
Running a virtual thread that holds a monitor across Thread.sleep(200)...
Done. If jdk.tracePinnedThreads still worked on this JDK, a pinned-thread stack trace would have printed above while the virtual thread was inside doWorkHoldingMonitor.

RESULT: no pinned-thread stack trace was printed by either run -- the flag is inert on this JDK, consistent with JEP 491