@Override
	public boolean equals(Object obj) {
		// 性能优化：比较操作有可能很昂贵
		if (this == obj)
			return true;

		if (! (obj instanceof PossibleError))
			return false;

		PossibleError other = (PossibleError) obj;
		return names == null ? other.names == null : names.equals(other.names);
	}