diff -r 118057a1093b -r f2d16e75bcf1 src/Doc/System/Environment.thy
--- a/src/Doc/System/Environment.thy	Thu Jul 15 22:14:11 2021 +0200
+++ b/src/Doc/System/Environment.thy	Thu Jul 15 22:28:26 2021 +0200
@@ -459,7 +459,7 @@
 text \<open>
   The subsequent example creates a raw Java process on the command-line and
   invokes the main Isabelle application entry point:
-  @{verbatim [display] \<open>isabelle_java isabelle.jedit.Main\<close>}
+  @{verbatim [display] \<open>isabelle_java -Djava.awt.headless=false isabelle.jedit.Main\<close>}
 \<close>