public static Class<?> findCommonElementType(Collection<?> collection) {
		if (isEmpty(collection)) {
			return null;
		}
		Class<?> candidate = null;
		for (Object val : collection) {
			if (val != null) {
				if (candidate == null) {
					candidate = val.getClass();
				} else if (candidate != val.getClass()) {
					return null;
				}
			}
		}
		return candidate;
	}