线程“Thread-10”中出现异常。数据访问应用程序使用无效异常：实体[in.happysellers.hdb.gold.orders.DummyTable]中属性[产品]的类型[类java.util.可选]未知;只允许基元类型和基元类型的集合或Map
我已经手动插入值在cassandra表，并尝试通过查询获取，它是给我正确的记录，那么为什么我不能保存记录通过代码使用optional.我认为应该有一些注解使用可选值在repo文件，我无法找到.

package in.happysellers.hdb.gold.orders

import in.happysellers.utils.DateTimeUtils
import org.hibernate.annotations.Type
import org.springframework.data.cassandra.core.cql.PrimaryKeyType
import org.springframework.data.cassandra.core.mapping.{Column, PrimaryKeyColumn, Table}
import org.springframework.lang.Nullable

import java.sql.Timestamp
import java.util.Optional
import javax.persistence._

@Table("dummy_table")
class DummyTable private {

  @Id
  @PrimaryKeyColumn(name = "user_id", `type` = PrimaryKeyType.PARTITIONED)
  var userId: Long = _

  @Column("product")
  @Nullable
  var product: Optional[String] = _

  @Column("product_details")
  @Nullable
  var productDetails: Optional[String] = _

  @Column("quantity")
  var quantity: Int = _

  @Column("cost")
  var cost: Float = _

  @PrimaryKeyColumn(name = "created_at", `type` = PrimaryKeyType.CLUSTERED)
  var createdAt: Timestamp = _

  def this(userId: Long, product: Optional[String],productDetails: Optional[String], quantity: Int, cost: Float) {
    this()
    this.userId = userId
    this.product = product
    this.productDetails = productDetails
    this.quantity = quantity
    this.cost = cost
    this.createdAt = DateTimeUtils.currentTimestamp
  }
}