@Entity
@Table(name = "t_person")
public class Person {

   @Id
   @Column(name = "person_id")
   @GeneratedValue(strategy = GenerationType.AUTO)
   private Long id;
   
        private Set<Character> characters ;
   
   @CollectionOfElements
   public Set<Character> getCharacters() {
        return this.characters;
        }

   public void setCharacters(Set<Character> characters) {
      this.characters = characters;
   }

}

and:

public enum Character {
    GENTLE,
    NORMAL,
    AGGRESSIVE,
    ATTENTIVE,
    VIOLENT,
    CRAFTY
}

@CollectionOfElements
private Set<Character> characters ;

@Embeddable
public class Register {

   @CollectionOfElements
   @Enumerated(EnumType.STRING)
   private Set<RegisterType> registerTypes;
   
   @Column(nullable = true)
   private String wsUsername;
   
   @Column(nullable = true)
   private String wsPassword;

   enum RegisterType {
      AKTOR("Aktør"), BEVILLING("Bevilling"), MOTORFERDSEL("Motorferdsel");

      private String label;
      private String location;

      RegisterType(String label) {
         this.label = label;
      }

      public String getLocation() {
         return location;
      }

      public void setLocation(String location) {
         this.location = location;
      }

      public String getLabel() {
         return label;
      }

      @Override
      public String toString() {
         return getLabel();
      }
   }

//Getters and setters
}

javax.persistence.PersistenceException: org.hibernate.MappingException: Could not determine type for: java.util.Set, for columns: [org.hibernate.mapping.Column(registerTypes)]