Wrong behavior of @watch() annotation in property reactivity when excluding all but one property

Issue

I added @watch(!*, a) like below so as to watch only property a, but property reactivity worked for all the properties of the fact object unexpectedly.

rule "rule-1"
    when
        $fact: FactX(convertToClassifiedString(a) == "LARGE") @watch(!*, a)
    then
        System.out.println("***** Action of rule-1");
        modify($fact) { setD("OK") };
end