code: @Override
  	public String initValues(final FieldCase ca) {
  		if (ca != null) {
  			/*
  			 * If a FieldCase is given all fields will be generated anew, independent of the case
  			 * combination.
  			 */
  			for (Constraint c : constraints) {
  				c.resetValues();
  			}
  		}
  		for (Constraint c : constraints) {
  			c.initValues(ca);
  		}
  		return null;
  	}
docs: Initializes all subconstraints.
  
  @return always {@code null}