@Override
 public CustomerBrokerNegotiation createSale(
     ActorIdentity cryptoCustomer, Collection<Clause> clauses)
     throws CantCreateSaleNegotiationException {
   try {
     return saleNegotiationManager.createNegotiation(
         cryptoCustomer.getPublicKey(), identity.getPublicKey());
   } catch (CantCreateCustomerBrokerSaleNegotiationException exception) {
     throw new CantCreateSaleNegotiationException(
         CantCreateSaleNegotiationException.DEFAULT_MESSAGE, exception, "", "");
   }
 }
 @Override
 public int hashCode() {
   int c = 0;
   c += identity.hashCode();
   return HASH_PRIME_NUMBER_PRODUCT * HASH_PRIME_NUMBER_ADD + c;
 }