fix(jsonrpc): correct TransactionResult.nonce per JSON-RPC spec (tronprotocol#6709)

Per ethereum/execution-apis, TransactionInfo.nonce is `uint` (QUANTITY)
and must match `^0x(0|[1-9a-f][0-9a-f]*)$`. java-tron emitted the field
as `0x0000000000000000` via `ByteArray.toJsonHex(new byte[8])`, which
violates the pattern. Both `TransactionResult` constructors now emit
`"0x0"`.

Block.nonce is intentionally left at `0x0000000000000000` because the
Block schema defines it as `bytes8`, so that value is already compliant
and shortening it would break conformance.

Closes tronprotocol#6547

Author: waynercheung

framework/src/main/java/org/tron/core/services/jsonrpc/types/TransactionResult.java

@@ -98,7 +98,7 @@ public TransactionResult(BlockCapsule blockCapsule, int index, Protocol.Transact
     TransactionCapsule capsule = new TransactionCapsule(tx);
     byte[] txId = capsule.getTransactionId().getBytes();
     hash = ByteArray.toJsonHex(txId);
-    nonce = ByteArray.toJsonHex(new byte[8]); // no value
+    nonce = "0x0"; // no value, QUANTITY type per Ethereum JSON-RPC spec
     blockHash = ByteArray.toJsonHex(blockCapsule.getBlockId().getBytes());
     blockNumber = ByteArray.toJsonHex(blockCapsule.getNum());
     transactionIndex = ByteArray.toJsonHex(index);
@@ -133,7 +133,7 @@ public TransactionResult(Transaction tx, Wallet wallet) {
     TransactionCapsule capsule = new TransactionCapsule(tx);
     byte[] txId = capsule.getTransactionId().getBytes();
     hash = ByteArray.toJsonHex(txId);
-    nonce = ByteArray.toJsonHex(new byte[8]); // no value
+    nonce = "0x0"; // no value, QUANTITY type per Ethereum JSON-RPC spec
     blockHash = "0x";
     blockNumber = "0x";
     transactionIndex = "0x";

framework/src/test/java/org/tron/core/services/jsonrpc/TransactionResultTest.java

@@ -23,10 +23,18 @@ public class TransactionResultTest extends BaseTest {
   private static final String OWNER_ADDRESS = "41548794500882809695a8a687866e76d4271a1abc";
   private static final String CONTRACT_ADDRESS = "A0B4750E2CD76E19DCA331BF5D089B71C3C2798548";
 
+  // QUANTITY pattern from ethereum/execution-apis base-types schema (uint).
+  private static final String QUANTITY_PATTERN = "^0x(0|[1-9a-f][0-9a-f]*)$";
+
   static {
     Args.setParam(new String[] {"-d", dbPath()}, TestConstants.TEST_CONF);
   }
 
+  private static void assertQuantity(String value) {
+    Assert.assertNotNull(value);
+    Assert.assertTrue("not a valid QUANTITY: " + value, value.matches(QUANTITY_PATTERN));
+  }
+
   @Test
   public void testBuildTransactionResultWithBlock() {
     SmartContractOuterClass.TriggerSmartContract.Builder builder2 =
@@ -49,6 +57,8 @@ public void testBuildTransactionResultWithBlock() {
         transactionResult.getHash());
     Assert.assertEquals(transactionResult.getGasPrice(), "0x1");
     Assert.assertEquals(transactionResult.getGas(), "0x64");
+    Assert.assertEquals("0x0", transactionResult.getNonce());
+    assertQuantity(transactionResult.getNonce());
   }
 
   @Test
@@ -65,7 +75,8 @@ public void testBuildTransactionResult() {
     Assert.assertEquals("0x5691531881bc44adbc722060d85fdf29265823db8e884b0d104fcfbba253cf11",
         transactionResult.getHash());
     Assert.assertEquals(transactionResult.getGasPrice(), "0x");
-    Assert.assertEquals(transactionResult.getNonce(), "0x0000000000000000");
+    Assert.assertEquals("0x0", transactionResult.getNonce());
+    assertQuantity(transactionResult.getNonce());
   }
 
 }