avoid jdk-11.0.6+10: it shows problem "S8217731: Font rendering and glyph spacing changed from jdk-8 to jdk-11" https://bugs.openjdk.java.net/browse/JDK-8217731 even though the changelog claims to have resolved this;
#!/usr/bin/env bash
#
# Author: Markus Wenzel, TU Muenchen
#
# DESCRIPTION: run a program in a modified environment
## diagnostics
PRG="$(basename "$0")"
function usage()
{
echo
echo "Usage: isabelle $PRG [CMDLINE ...]"
echo
echo
echo " Run CMDLINE within the Isabelle environment (via the system's env command)."
echo
exit 1
}
## main
[ "$1" = "-?" ] && usage
exec /usr/bin/env "$@"