TradeRoundTripBuilder implements IRoundTripBuilder { @Override public IRoundTrip buildRoundTrip() { return new TradeRoundTrip(); }  @Override IRoundTrip buildRoundTrip();  }
@Test public void testBuildRoundTrip() { TradeRoundTripBuilder builder = new TradeRoundTripBuilder(); IRoundTrip trip = builder.buildRoundTrip(); assertTrue( trip instanceof TradeRoundTrip ); }