Need a test to verify if Module::getResourceAsStream handles properly with null caller.   Same verification is needed for Class::getResourceAsStream.

        if (isNamed() && Resources.canEncapsulate(name)) {
            Module caller = getCallerModule(Reflection.getCallerClass());
            if (caller != this && caller != Object.class.getModule()) {
                String pn = Resources.toPackageName(name);
                if (getPackages().contains(pn)) {
                    if (caller == null && !isOpen(pn)) {
                        // no caller, package not open
                        return null;
                    }
                    if (!isOpen(pn, caller)) {
                        // package not open to caller
                        return null;
                    }
                }
            }
        }