Probe records class load and unload events.
Results are available in the probes UI in tab "Class loading".
You can quickly access them from "Classes" telemetry clicking link "Detail...":
There is no source code available for this probe, as it is based on low-level JVM events, available via native API only (JVMTI).
This probe has no associated probe class (see above), thus a pseudo-name
should be used in corresponding startup options,
probe_off=com.yourkit.probes.builtin.ClassLoading disables the class loading probe.