docs: public Object execute(final Object value, final CsvContext context) {
  		if( UNKNOWN.equals(constantValue) ) {
  			constantValue = value; // no constant supplied, so remember the first value encountered
  		} else {
  			if( !equals(constantValue, value) ) {
  				if( constantSupplied ) {
  					throw new SuperCsvConstraintViolationException(String.format("'%s' is not equal to the supplied constant '%s'", value,
  						constantValue), context, this);
  				} else {
  					throw new SuperCsvConstraintViolationException(String.format("'%s' is not equal to the previous value(s) of '%s'",
  						value, constantValue), context, this);
  				}
  			}
  		}
  		return next.execute(value, context);
  	}