nonce as integer for preloaded contracts (hyperledger#7850)

* fixes hyperledger#7749
Signed-off-by: vaidikcode <vaidikbhardwaj00@gmail.com>

* tests
Signed-off-by: vaidikcode <vaidikbhardwaj00@gmail.com>

* spotless format fix
Signed-off-by: vaidikcode <vaidikbhardwaj00@gmail.com>

---------

Co-authored-by: Sally MacFarlane <macfarla.github@gmail.com>
Co-authored-by: Fabio Di Fabio <fabio.difabio@consensys.net>

config/src/main/java/org/hyperledger/besu/config/GenesisReader.java

@@ -80,7 +80,9 @@ public Stream<GenesisAccount> streamAllocations() {
                 final var on = normalizeKeys((ObjectNode) entry.getValue());
                 return new GenesisAccount(
                     Address.fromHexString(entry.getKey()),
-                    JsonUtil.getString(on, "nonce").map(ParserUtils::parseUnsignedLong).orElse(0L),
+                    JsonUtil.getValueAsString(on, "nonce")
+                        .map(ParserUtils::parseUnsignedLong)
+                        .orElse(0L),
                     JsonUtil.getString(on, "balance")
                         .map(ParserUtils::parseBalance)
                         .orElse(Wei.ZERO),

config/src/test/java/org/hyperledger/besu/config/GenesisReaderTest.java

@@ -17,6 +17,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.hyperledger.besu.config.GenesisReader.ALLOCATION_FIELD;
 import static org.hyperledger.besu.config.GenesisReader.CONFIG_FIELD;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import org.hyperledger.besu.datatypes.Address;
 import org.hyperledger.besu.datatypes.Wei;
@@ -27,6 +28,7 @@
 import java.util.Map;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
@@ -111,4 +113,17 @@ private ObjectNode generateAllocation(final Wei balance) {
     entry.put("balance", balance.toShortHexString());
     return entry;
   }
+
+  @Test
+  void testNonceHandlingAsStringAndInteger() {
+    ObjectNode accountNode = JsonNodeFactory.instance.objectNode();
+
+    accountNode.put("nonce", 10);
+    String nonceAsStringFromInt = JsonUtil.getValueAsString(accountNode, "nonce").orElse("");
+    assertEquals("10", nonceAsStringFromInt, "Nonce should convert integer to string correctly");
+
+    accountNode.put("nonce", "20");
+    String nonceAsStringDirect = JsonUtil.getValueAsString(accountNode, "nonce").orElse("");
+    assertEquals("20", nonceAsStringDirect, "Nonce should keep string as string correctly");
+  }
 }