ManageSellOfferOperation constructor
Implementation
ManageSellOfferOperation(Asset selling, Asset buying, String amount,
String price, String offerId) {
this._selling = checkNotNull(selling, "selling cannot be null");
this._buying = checkNotNull(buying, "buying cannot be null");
this._amount = checkNotNull(amount, "amount cannot be null");
this._price = checkNotNull(price, "price cannot be null");
this._offerId = offerId;
}