public void set(int id) {
        //assert this != SOME;
        assert this != ALL;
        assert this != NONE;

        agent.set(id);
    }
A wrapper of the underlying bitmap.

We guarantee that the content of {@link #ALL} or {@link #NONE} will never be changed.
As those static instances are shared around.
indexr-common/src/main/java/io/indexr/util/BitMap.java