How to change ObjectProperty to DoubleBinding

Question

How to change ObjectProperty to DoubleBinding and then put into Bindings.createObjectBinding();

private transient ObjectProperty<BigDecimal>  buy;
private transient ObjectProperty<BigDecimal>  sell;

There are the mistake:

buy = Bindings.createObjectBinding(() -> (operation.get() == Operation.BUY) ? volume.get() : 0, volume, operation);

sell = Bindings.createDoubleBinding(() -> (operation.get() == Operation.SELL) ? volume.get() : 0, volume, operation);