/**
  * Create a standard pay to address output for usage in {@link #createPaymentRequest} and {@link
  * #createPaymentMessage}.
  *
  * @param amount amount to pay, or null
  * @param address address to pay to
  * @return output
  */
 public static Protos.Output createPayToAddressOutput(@Nullable Coin amount, Address address) {
   Protos.Output.Builder output = Protos.Output.newBuilder();
   if (amount != null) {
     final NetworkParameters params = address.getParameters();
     if (params.hasMaxMoney() && amount.compareTo(params.getMaxMoney()) > 0)
       throw new IllegalArgumentException("Amount too big: " + amount);
     output.setAmount(amount.value);
   } else {
     output.setAmount(0);
   }
   output.setScript(ByteString.copyFrom(ScriptBuilder.createOutputScript(address).getProgram()));
   return output.build();
 }
 @Test
 public void empty() throws Exception {
   // Check the base case of a wallet with one key and no transactions.
   Wallet wallet1 = roundTrip(myWallet);
   assertEquals(0, wallet1.getTransactions(true).size());
   assertEquals(Coin.ZERO, wallet1.getBalance());
   assertArrayEquals(
       myKey.getPubKey(), wallet1.findKeyFromPubHash(myKey.getPubKeyHash()).getPubKey());
   assertArrayEquals(
       myKey.getPrivKeyBytes(),
       wallet1.findKeyFromPubHash(myKey.getPubKeyHash()).getPrivKeyBytes());
   assertEquals(
       myKey.getCreationTimeSeconds(),
       wallet1.findKeyFromPubHash(myKey.getPubKeyHash()).getCreationTimeSeconds());
   assertEquals(mScriptCreationTime, wallet1.getWatchedScripts().get(0).getCreationTimeSeconds());
   assertEquals(1, wallet1.getWatchedScripts().size());
   assertEquals(
       ScriptBuilder.createOutputScript(myWatchedKey.toAddress(params)),
       wallet1.getWatchedScripts().get(0));
   assertEquals(WALLET_DESCRIPTION, wallet1.getDescription());
 }