What is the Spring Data Cassandra mapping annotation for NOT NULL constraint?

Say for example, this entity class:

import org.springframework.data.cassandra.core.mapping.Column;
import org.springframework.data.cassandra.core.mapping.Table;
import org.springframework.data.cassandra.core.mapping.PrimaryKey;

@Table(value = "login_event")
public class LoginEvent {

  private LoginEventKey key;

  private String ipAddress;

  // getters and setters omitted

I would like to make the "ip_address" field NOT NULL in the database table, how to achieve that? thanks!