private Exchange createExchange() {
Exchange exchange = new Exchange();
exchange.id = 1;
exchange.meanAmount = (double) 500;
ExchangeExtension extension = new ExchangeExtension(exchange);
extension.setAmount(42);
extension.setFormula("2 * Pi * sqr(r)");
extension.setPropertyId("property-id");
extension.setUnitId("unit-id");
extension.setDefaultProvider("abc-def");
extension.setAvoidedProduct(true);
return exchange;
}