diff -r 8cbe519c2085 -r 9e71155e3666 lib/Tools/java_monitor
--- a/lib/Tools/java_monitor	Fri Sep 24 12:53:11 2021 +0200
+++ b/lib/Tools/java_monitor	Fri Sep 24 13:40:14 2021 +0200
@@ -4,4 +4,4 @@
 #
 # DESCRIPTION: monitor another Java process
 
-isabelle java "-Dapple.awt.application.name=Java Monitor" isabelle.Java_Monitor "$@"
+isabelle java "-Dapple.awt.application.name=Java Monitor" --add-opens jdk.jconsole/sun.tools.jconsole=ALL-UNNAMED isabelle.Java_Monitor "$@"