Hints engine ignore equals method tests. Equals method return false, if argument is null. This method can be considered for possible null hint.

Example code:

    @Nonnull
    public static String test(@Nullable String value){
        if(!"test".equals(value)){
            return "something";
        }
        return value;
    }

Netbeans report possible null on "return value;". But this is not possible, because of equals test.

It is easy to understand for programmer. I'm not sure, if it would be possible to include this in hints engine.