static field shared between instances of generic

The documentation says that one implementation is shared. I guess it makes sense this translates to one copy of the class variables getting shared as well.

public class GenericStatic<T> {
    static String o = "";
    String oo() {
 return o += "o";
    }

    public static void main(String[] args) {
 GenericStatic<Object> a = new GenericStatic<Object>();
 GenericStatic<String> b = new GenericStatic<String>();
 System.out.println(a.oo());
 System.out.println(b.oo());
    }
}

$ javac GenericStatic.java
$ java GenericStatic
o
oo