title: How to persist a property of type List<List<Object>> in JPA?
body: <p>What is the smartest way to get an entity with a field of type List&lt;List&gt; persisted?</p>
  <pre><code>@Entity
  </code></pre>
  <p>@Table(name = &quot;Final_Feign_Client_Result&quot;)
  public class FinalFCResultEntity {</p>
  <pre><code>@Id
  @Column(name = &quot;id&quot;)
  @GeneratedValue(strategy = IDENTITY)
  private Integer id;
  
  @ElementCollection(targetClass = Object.class)
  @CollectionTable(name = &quot;Final_Feign_Client_Result_Columns&quot;)
  @OnDelete(action = OnDeleteAction.CASCADE)
  @JoinColumn(name = &quot;final_feign_client_result_entity_id&quot;, nullable = false)
  private Set&lt;Object&gt; values;
  
  public Integer getId() {
      return id;
  }
  
  public void setId(Integer id) {
      this.id = id;
  }
  
  public Set&lt;Object&gt; getValues() {
      return values;
  }
  
  public void setValues(Set&lt;Object&gt; values) {
      this.values = values;
  }
  </code></pre>
  <p>}
  I have no problem with columns, but if I try to insert values I get this exception:</p>
  <pre><code>Caused by: org.hibernate.MappingException: Could not determine type for: java.util.List, at table: final_feign_client_result_columns, for columns: [org.hibernate.mapping.Column(values)]
  </code></pre>
  <p>How I can solve this problem?</p>