hollow/src/main/java/com/netflix/hollow/core/read/engine/HollowTypeReadState.java
public void addListener(HollowTypeStateListener listener) {
        HollowTypeStateListener[] newListeners = Arrays.copyOf(stateListeners, stateListeners.length + 1);
        newListeners[newListeners.length - 1] = listener;
        stateListeners = newListeners;
    }
public void addListener(HollowTypeStateListener listener) {
        HollowTypeStateListener[] newListeners = Arrays.copyOf(stateListeners, stateListeners.length + 1);
        newListeners[newListeners.length - 1] = listener;
        stateListeners = newListeners;
    }
Add a {@link HollowTypeStateListener} to this type.
@param listener the listener to add