private static boolean isParent(IGroup groupToBeTested, IGroup parentGroup) {
		if (groupToBeTested.isGroup() == false) {
			// Very strange!
			return false;
		}
		if (groupToBeTested.isGroup() == false) {
			throw new IllegalArgumentException();
		}
		while (EntityUtils.groupRoot(groupToBeTested) == false) {
			if (groupToBeTested == parentGroup) {
				return true;
			}
			groupToBeTested = groupToBeTested.getParentContainer();
			if (groupToBeTested.isGroup() == false) {
				throw new IllegalStateException();
			}
		}
		return false;
	}