Spring mvc not able to receive a Set of string

hibernate

I have an entity: Factories

@Entity
public class Factories extends BaseEntity {

    @Id
    @SequenceGenerator(name = "factories_id_seq", sequenceName = "factories_id_seq", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "factories_id_seq")
    private Integer id;


    @ElementCollection
    private Set<String> emails = new HashSet<String>();

    //get set...
}

In thymeleaf to add email to factories,

 <table id="emailsTable" class="table table-striped table-hover responsive">
      <thead>
          <tr>
              <th th:text="#{value}">Value</th>
              <th></th>
          </tr>
      </thead>
      <tbody>
          <tr th:each="email, stat : *{emails}">
              <td><input type="text" class="form-control" th:placeholder="#{email.placeholder}" placeholder="Name" th:field="*{emails[__${stat.index}__]}" /></td>
              <td class="align-middle"><button type="button" class="btn btn-default pull-right delete"><i class="fas fa-trash-alt"></i></button></td>
          </tr>
      </tbody>
</table>

When I try to save, I get

org.springframework.beans.InvalidPropertyException: Invalid property 'emails[0]' of bean class [com.lcm.model.Factories]: Property referenced in indexed property path 'emails[0]' is neither an array nor a List nor a Map; returned value was [[]]