Jackson doesn't serialize version field

Question

I'm using Spring boot 1.5.3 with Spring Data Rest and JPA. I'm experiencing a very strange problem.

This is the superclass of my entity beans:

@EntityListeners({ AuditingEntityListener.class })
@MappedSuperclass
@Audited
public abstract class AbstractEntity extends AbstractPersistable<Long> {
    private static final long serialVersionUID = 1L;

    /* "UUID" and "UID" are Oracle reserved keywords -> "sid" */
    @Column(name = "sid", unique = true, nullable = false, updatable = false, length = 36)
    private String sid;

    @CreatedBy
    private String createdBy;

    @CreatedDate
    @Column(updatable = false)
    private LocalDateTime createdDate;

    @LastModifiedDate
    private LocalDateTime lastModifiedDate;

    @LastModifiedBy
    private String lastModifiedBy;

    // Trick to start version counting from 1 instead of 0
    @Version
    private int version = 1;

    public AbstractEntity() {
    }

    @PrePersist
    public void initializeUUID() {
        if (sid == null) {
            sid = UUID.randomUUID().toString();
        }
    }

    public String getSid() {
        return sid;
    }

    public LocalDateTime getCreatedDate() {
        return createdDate;
    }

    public LocalDateTime getLastModifiedDate() {
        return lastModifiedDate;
    }

    public String getLastModifiedBy() {
        return lastModifiedBy;
    }

    public int getVersion() {
        return version;
    }

    @Override
    public boolean equals(Object o) {
        return (o == this || (o instanceof AbstractEntity && sid.equals(((AbstractEntity) o).sid)));
    }

    @Override
    public int hashCode() {
        return sid.hashCode();
    }

}

This is a entity I persist:

@Entity
public class Country extends AbstractEntity {
    private static final long serialVersionUID = 4487829062553023011L;

    @Audited
    @NotNull(message = "The name cannot be empty")
    @Column(nullable = false)
    private String name;

    @Audited
    @NotNull(message = "The ISO code cannot be empty")
    @Size(min = 2, max = 2)
    @Column(nullable = false, unique = true)
    private String isoCode;

    public Country() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getIsoCode() {
        return isoCode;
    }

    public void setIsoCode(String isoCode) {
        this.isoCode = isoCode;
    }

}

When I look at Swagger I see a correct definition of the model:

Country {
    createdDate (string, optional),
    id (integer, optional),
    isoCode (string),
    lastModifiedBy (string, optional),
    lastModifiedDate (string, optional),
    name (string),
    new (boolean, optional),
    sid (string, optional),
    version (integer, optional)
}

But when I asked for the all countries or for a specific country the version field is not visible:

{
  "sid": "cd2527a0-4667-4d25-a098-70f12bfed2da",
  "createdDate": "2017-06-22T11:02:48",
  "lastModifiedDate": "2017-06-22T11:02:48",
  "lastModifiedBy": null,
  "name": "Italy",
  "isoCode": "IT",
  "new": false,
  "_links": {
    "self": {
      "href": "http://localhost:8080/api/v1/countries/1"
    },
    "country": {
      "href": "http://localhost:8080/api/v1/countries/1"
    }
  }

}

I thought it was a problem of a reserved keyword but it's not. Also renaming the field it is present in the model but not in the return data.

Am I doing something wrong? I need the version because Hibernate needs that to persist correctly.