// No point in checking boot class path, can't reload those.
// else we could have used fullClassPath above.
if ( o == null )
throw new ClassPathException("Nothing known about class: "
+name );
if ( ! (o instanceof DirClassSource) )
throw new ClassPathException("Cannot reload class: "+name+
" from source: "+o);
map.put( name, ((DirClassSource)o).getDir() );
}