@Override
    public String toString() {
        return "NodeFlagPair{" +
                "on=" + on +
                ", off=" + off +
                '}';
    }
Adds nodeFlag to the provided flags set after removing the other member of this {@link NodeFlagPair}

@param isOn  The flag to add based on its state
@param flags Set to add to
stroom-core-shared/src/main/java/stroom/explorer/shared/NodeFlagPair.java