/** Disables the Validation by setting empty constraints. */
  private void doRemoveValidation() {

    setValidationOn(false);

    artNr.setConstraint("");
    aupMenge.setConstraint("");
    aupEinzelwert.setConstraint("");
    aupGesamtwert.setConstraint("");
  }
  /** Sets the Validation by setting the accordingly constraints to the fields. */
  private void doSetValidation() {

    setValidationOn(true);

    artNr.setConstraint(new SimpleConstraint("NO EMPTY"));
    aupMenge.setConstraint("NO EMPTY, NO ZERO");
    aupEinzelwert.setConstraint("NO EMPTY, NO ZERO");
    aupGesamtwert.setConstraint("NO EMPTY, NO ZERO");
  }