code: @MustBeLocked (ELockType.WRITE)
    @OverridingMethodsMustInvokeSuper
    protected void markAsChanged (@Nonnull final DATATYPE aModifiedElement, @Nonnull final EDAOActionType eActionType)
    {
      ValueEnforcer.notNull (aModifiedElement, "ModifiedElement");
      ValueEnforcer.notNull (eActionType, "ActionType");
  
      // Convert single item to list
      markAsChanged (new CommonsArrayList <> (aModifiedElement), eActionType);
    }
docs: This method must be called every time something changed in the DAO. It
  triggers the writing to a file if auto-save is active. This method must be
  called within a write-lock as it is not locked!
  
  @param aModifiedElement
  The modified data element. May not be <code>null</code>.
  @param eActionType
  The action that was performed. May not be <code>null</code>.