synchronized void classNameChanged(String oldname, CtClass clazz) {
        CtClass c = (CtClass)getCached(oldname);
        if (c == clazz)             // must check this equation.
            removeCached(oldname);  // see getAndRename().

        String newName = clazz.getName();
        checkNotFrozen(newName);
        cacheCtClass(newName, clazz, false);
    }