@MappedSuperclass
public class UniqueEntity implements Serializable {

  public static final String UUID_NULL = "00000000-0000-0000-0000-000000000000";

  private static final long serialVersionUID = -3610403242496914987L;

  @Id
  @Column(columnDefinition = "uniqueidentifier")
  private String uuid;

  protected UniqueEntity() {
    this.setUuid(UUID.randomUUID().toString().toUpperCase());
  }

  public UniqueEntity(String uuid) {
    this.setUuid(UUID.fromString(uuid).toString().toUpperCase());
  }

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

  @Override
  public boolean equals(java.lang.Object object) {
    if (object instanceof UniqueEntity) {
      return this.getUuid().equals(((UniqueEntity) object).getUuid());
    }
    if (object instanceof String) {
      return this.getUuid().equals(object);
    }
    return super.equals(object);
  }

  @Override
  public String toString() {
    return this.getUuid();
  }

  public String getUuid() {
    return this.uuid;
  }

  public void setUuid(String uuid) {
    this.uuid = uuid;
  }
}

@Entity(name = "Test")
@Table(name = "\"Test\"")
@AttributeOverride(name = "uuid",
    column = @Column(columnDefinition = "varchar", name = "\"uuid\"", length = 36))
public class Test extends UniqueEntity implements Serializable {

  private static final long serialVersionUID = -4887208830019935105L;
}

create table "Test" (
       "uuid" varchar not null,
        primary key ("uuid")
    )