more robust check of ISABELLE_PLATFORM_FAMILY within settings environment, to support its reunification with Isabelle/Scala (see also a33a6e541cbb, f3a356c64193);
#!/usr/bin/env bash
#
# Author: Makarius
#
# DESCRIPTION: invoke Java within the Isabelle environment
eval "declare -a JAVA_ARGS=($ISABELLE_JAVA_SYSTEM_OPTIONS)"
classpath "$ISABELLE_SETUP_CLASSPATH"; unset ISABELLE_SETUP_CLASSPATH
classpath "$CLASSPATH"; export CLASSPATH=""
isabelle_java java "${JAVA_ARGS[@]}" \
-classpath "$(platform_path "$ISABELLE_CLASSPATH")" "$@"