code: @PreUpdate
      @PrePersist
      private void changeAuditInformation(JodaAuditable auditableEntity) {
      	DateTime lastUpdated = new DateTime();
          auditableEntity.setLastUpdated(lastUpdated);
          String lastUpdatedBy = ServiceContextStore.getCurrentUser();
          auditableEntity.setLastUpdatedBy(lastUpdatedBy);
          if (auditableEntity.getCreatedDate() == null)
              auditableEntity.setCreatedDate(lastUpdated);
          if (auditableEntity.getCreatedBy() == null)
              auditableEntity.setCreatedBy(lastUpdatedBy);
      }
docs: set audit informations, doesn't modify createdDate and createdBy once
  set. Only works with DomainObjects that implement the JodaAuditable
  interface. In other cases a IllegalArgumentException is thrown.
  
  @param entity
  @return