Their jar files reference other non-URE jars, so they cannot be extensions.
bsh.jar has been moved into the optional module (it used to be installed
always, but it looks like only the bsh script provider needs it; also, it
had been added to URE_MORE_JAVA_CLASSPATH_URLS if SYSTEM_BSH, which also
appears unnecessary as it is mentioned with an absolute file URL in the
Class-Path of the script provider jar).
js.jar has been included in the optional module (it used to be not installed
at all?).