Avoid a cyclic reference while printing EngineExchangeTransitionConfigurationParameter

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/methods/engine/EngineExchangeTransitionConfiguration.java

@@ -30,9 +30,12 @@
 import org.hyperledger.besu.ethereum.core.Difficulty;
 
 import java.util.Optional;
+import java.util.function.Supplier;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.base.Suppliers;
 import io.vertx.core.Vertx;
-import io.vertx.core.json.Json;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -45,6 +48,8 @@ public class EngineExchangeTransitionConfiguration extends ExecutionEngineJsonRp
       Difficulty.fromHexString(
           "0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffc00");
 
+  private static final Supplier<ObjectMapper> mapperSupplier = Suppliers.memoize(ObjectMapper::new);
+
   public EngineExchangeTransitionConfiguration(
       final Vertx vertx,
       final ProtocolContext protocolContext,
@@ -69,7 +74,13 @@ public JsonRpcResponse syncResponse(final JsonRpcRequestContext requestContext)
     traceLambda(
         LOG,
         "received transitionConfiguration: {}",
-        () -> Json.encodePrettily(remoteTransitionConfiguration));
+        () -> {
+          try {
+            return mapperSupplier.get().writeValueAsString(remoteTransitionConfiguration);
+          } catch (JsonProcessingException e) {
+            throw new RuntimeException(e);
+          }
+        });
 
     final Optional<BlockHeader> maybeTerminalPoWBlockHeader =
         mergeContextOptional.flatMap(MergeContext::getTerminalPoWBlock);

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/parameters/EngineExchangeTransitionConfigurationParameter.java

@@ -39,10 +39,20 @@ public Difficulty getTerminalTotalDifficulty() {
     return terminalTotalDifficulty;
   }
 
+  @JsonProperty("terminalTotalDifficulty")
+  public String getTerminalTotalDifficultyAsHexString() {
+    return terminalTotalDifficulty.toShortHexString();
+  }
+
   public Hash getTerminalBlockHash() {
     return terminalBlockHash;
   }
 
+  @JsonProperty("terminalBlockHash")
+  public String getTerminalBlockHashAsHexString() {
+    return terminalBlockHash.toShortHexString();
+  }
+
   public long getTerminalBlockNumber() {
     return terminalBlockNumber;
   }