XWiki Core APIs allowing groovy or velocity scripts to refer to classes in XWiki documents attached jar files

1/ Attach jar files in a wiki page
2/ It should be possible using a simple api to run classes attached in this jar files. For example:

$xwiki.parseGroovyFromPage("Test.TestGroovy", "Test.TestJarFiles")

Would run the groovy script in Test.TestGroovy which would contain references to classes in jar files attached to the Test.TestJarFiles page.