private void sendHelp(final HttpServerRequest req, final ObjectMapper objectMapper) {
    ObjectNode outputObject = objectMapper.createObjectNode();
    outputObject.set("version", TextNode.valueOf(new VersionProvider().getVersion()[0]));
    ArrayNode forks = objectMapper.createArrayNode();
    outputObject.set("forks", forks);
    for (var fork : EvmSpecVersion.values()) {
      forks.add(TextNode.valueOf(fork.getName()));
    }
    outputObject.set("error", TextNode.valueOf("Both 'state' and 'input' fields must be set"));

    try {
      req.response()
          .putHeader("Content-Type", "application/json")
          .end(objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(outputObject));

    } catch (JsonProcessingException e) {
      req.response().setStatusCode(500).end(e.getMessage());
    }
  }
Default constructor for the T8nServerSubCommand class. This constructor is required by PicoCLI
and assigns null to parentCommand.
ethereum/evmtool/src/main/java/org/hyperledger/besu/evmtool/T8nServerSubCommand.java