这看起来像一个Cassandra错误（参见 https://issues.apache.org/jira/browse/CASSANDRA-11549 ）。我还没有能够找到一种方式让Cassandra接受null。你可能需要坚持一个解决方法，现在用一些哨兵的值替换null。

This looks like a Cassandra bug (see https://issues.apache.org/jira/browse/CASSANDRA-11549). I haven't been able to find a way to get Cassandra to accept the nulls. You may have to stick with a workaround for now substitute some sentinel value for the nulls.