fix: fix the issue where sending assets using TransactionBuilder.buildPaymentToContractTransaction fails when the sender's account is the same as the asset issuer's account. (#685)

Author: overcat

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Pending
 
+### Update:
+fix: fix the issue where sending assets using `TransactionBuilder.buildPaymentToContractTransaction` fails when the sender's account is the same as the asset issuer's account. ([#685](https://github.com/stellar/java-stellar-sdk/pull/685))
+
 ## 1.3.0
 
 ### Update:

src/main/java/org/stellar/sdk/TransactionBuilder.java

@@ -400,26 +400,27 @@ public Transaction buildPaymentToContractTransaction(
               .build());
       readWrite.add(balanceLedgerKey);
     } else {
+      String assetIssuer = ((AssetTypeCreditAlphaNum) asset).getIssuer();
       readOnly.add(
           LedgerKey.builder()
               .discriminant(LedgerEntryType.ACCOUNT)
               .account(
                   LedgerKey.LedgerKeyAccount.builder()
-                      .accountID(
-                          KeyPair.fromAccountId(((AssetTypeCreditAlphaNum) asset).getIssuer())
-                              .getXdrAccountId())
+                      .accountID(KeyPair.fromAccountId(assetIssuer).getXdrAccountId())
                       .build())
               .build());
       readOnly.add(contractInstanceLedgerKey);
-      readWrite.add(
-          LedgerKey.builder()
-              .discriminant(LedgerEntryType.TRUSTLINE)
-              .trustLine(
-                  LedgerKey.LedgerKeyTrustLine.builder()
-                      .accountID(KeyPair.fromAccountId(fromAddress).getXdrAccountId())
-                      .asset(new TrustLineAsset(asset).toXdr())
-                      .build())
-              .build());
+      if (!assetIssuer.equals(fromAddress)) {
+        readWrite.add(
+            LedgerKey.builder()
+                .discriminant(LedgerEntryType.TRUSTLINE)
+                .trustLine(
+                    LedgerKey.LedgerKeyTrustLine.builder()
+                        .accountID(KeyPair.fromAccountId(fromAddress).getXdrAccountId())
+                        .asset(new TrustLineAsset(asset).toXdr())
+                        .build())
+                .build());
+      }
       readWrite.add(balanceLedgerKey);
     }
 

src/test/java/org/stellar/sdk/TransactionTest.java

@@ -645,6 +645,51 @@ public void testIntegrationPaymentToContractTransactionWithAlphanum12Asset() thr
     server.close();
   }
 
+  @Test
+  public void testIntegrationPaymentToContractTransactionWithAssetIssuerAsSender()
+      throws IOException {
+    BigDecimal amount1 = new BigDecimal("100.125");
+    BigDecimal amount2 = new BigDecimal("120.7891");
+
+    KeyPair kp = KeyPair.random();
+    IntegrationUtils.fundAccount(kp.getAccountId());
+    Asset asset = Asset.createNonNativeAsset("CAT", kp.getAccountId());
+    IntegrationUtils.createAssetContract(asset, kp);
+    String destination = IntegrationUtils.getRandomContractId(kp);
+    Server server = new Server(IntegrationUtils.HORIZON_URL);
+    TransactionBuilderAccount sourceAccount = server.loadAccount(kp.getAccountId());
+
+    Transaction transaction1 =
+        new TransactionBuilder(sourceAccount, IntegrationUtils.NETWORK)
+            .setBaseFee(100)
+            .setTimeout(300)
+            .buildPaymentToContractTransaction(destination, asset, amount1, null);
+    transaction1.sign(kp);
+    server.submitTransaction(transaction1);
+    BigInteger balance1 = IntegrationUtils.getBalanceForContract(destination, asset, kp);
+    assertEquals(1001250000L, balance1.longValue());
+
+    Transaction transaction2 =
+        new TransactionBuilder(sourceAccount, IntegrationUtils.NETWORK)
+            .setBaseFee(100)
+            .setTimeout(300)
+            .buildPaymentToContractTransaction(destination, asset, amount2, null);
+    transaction2.sign(kp);
+    server.submitTransaction(transaction2);
+    BigInteger balance2 = IntegrationUtils.getBalanceForContract(destination, asset, kp);
+    assertEquals(2209141000L, balance2.longValue());
+
+    Transaction transaction3 =
+        new TransactionBuilder(sourceAccount, IntegrationUtils.NETWORK)
+            .setBaseFee(100)
+            .setTimeout(300)
+            .buildRestoreAssetBalanceEntryTransaction(destination, asset, null);
+    transaction3.sign(kp);
+    server.submitTransaction(transaction3);
+
+    server.close();
+  }
+
   @Test
   public void testIntegrationPaymentToContractTransactionWithDifferentSource() throws IOException {
     Asset asset = Asset.createNativeAsset();