code: @Override
  	public String initValues(final FieldCase ca) {
  		boolean found = false;
  		buffer.setLength(0);
  		for (Constraint c : constraints) {
  			String cV = c.initValues(ca);
  			if (cV != null) {
  				found = true;
  				buffer.append(cV);
  			}
  		}
  		if (found) {
  			return buffer.toString();
  		}
  		return null;
  	}
docs: Initializes all sub-constraints. Returns a character string composed of all character strings
  of the constraints contained in it. If all sub-constraints return null, null is returned.