fix: include nonce in TransactionId equals() method (#2555)

Signed-off-by: emiliyank <e.kadiyski@gmail.com>

Author: emiliyank

sdk/src/main/java/com/hedera/hashgraph/sdk/TransactionId.java

@@ -495,7 +495,10 @@ public boolean equals(Object object) {
         var id = (TransactionId) object;
 
         if (accountId != null && validStart != null && id.accountId != null && id.validStart != null) {
-            return id.accountId.equals(accountId) && id.validStart.equals(validStart) && scheduled == id.scheduled;
+            return id.accountId.equals(accountId)
+                    && id.validStart.equals(validStart)
+                    && scheduled == id.scheduled
+                    && Objects.equals(nonce, id.nonce);
         } else {
             return false;
         }

sdk/src/test/java/com/hedera/hashgraph/sdk/TransactionIdTest.java

@@ -3,6 +3,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 
 import com.google.protobuf.InvalidProtocolBufferException;
 import io.github.jsonSnapshot.SnapshotMatcher;
@@ -170,4 +171,19 @@ void shouldAddTrailingZeroesToNanoseconds() {
         var txId = TransactionId.fromString(txIdString);
         assertThat(txId).hasToString(txIdString);
     }
+
+    @Test
+    void equalsHashCodeContractWithNonce() {
+        AccountId accountId = new AccountId(0, 0, 1000);
+        Instant now = Instant.now();
+
+        TransactionId txnId1 = TransactionId.withValidStart(accountId, now);
+        TransactionId txnId2 = TransactionId.withValidStart(accountId, now);
+
+        txnId2.setNonce(0);
+
+        assertFalse(
+                txnId1.equals(txnId2) && txnId1.hashCode() != txnId2.hashCode(),
+                "equals/hashCode contract violation: equal objects must have same hashCode");
+    }
 }