Viewing the hudson pages in your web browser causes the java plugin for that
browser to start up even though hudson doesn't currently use any java applets.

It appears that the following code in hudson-behaviour.js is the culprit:

// are we run as unit tests?
var isRunAsTest = (function() {
try

{ return Packages.java.lang.System.getProperty("hudson.unitTest")!=null; }

catch(e)

{ return false; }

})();

If the System Property retrieval is removed then the java browser plugin no
longer initializes as a result of loading Hudson web pages.