make "Unprotected concurrency introduces some true randomness." be true;
this code is called often and doesn't need to be considered critical. I added CRITICAL by mistake.
#!/usr/bin/env bash
#
# Author: Makarius
#
# DESCRIPTION: invoke Java within the Isabelle environment
CLASSPATH="$(jvmpath "$CLASSPATH")"
exec "${THIS_JAVA:-$ISABELLE_JAVA}" "$@"