public static String packageName(Class<?> componentClass) {
        String fullClassName = componentClass.getName();
        int index = fullClassName.lastIndexOf('.');
        if (index < 0) {
            return "";
        } else {
            return fullClassName.substring(0, index);
        }
    }
@param identityObject he identifying object that makes the Node unique
container-core/src/main/java/com/yahoo/container/di/componentgraph/core/Node.java