The boot jars of Graal.js are added by a separate component.

ansalond · ansalond · commit c9402a32bc6d · 2022-09-16T14:34:51.000+02:00
diff --git a/graal-js/mx.graal-js/mx_graal_js.py b/graal-js/mx.graal-js/mx_graal_js.py
@@ -373,7 +373,7 @@ def is_included(path):
             language='js',
         )
     ],
-    boot_jars=['graal-js:GRAALJS_SCRIPTENGINE'],
+    boot_jars=[],
     installable=True,
     stability="supported",
 ))

Original file line number	Diff line number	Diff line change
`@@ -373,7 +373,7 @@ def is_included(path):`
`373`	`373`	`language='js',`
`374`	`374`	`)`
`375`	`375`	`],`
`376`		`- boot_jars=['graal-js:GRAALJS_SCRIPTENGINE'],`
	`376`	`+ boot_jars=[],`
`377`	`377`	`installable=True,`
`378`	`378`	`stability="supported",`
`379`	`379`	`))`