private Optional<Hash> getOptionalHash(final String key) {
    if (configOverrides.containsKey(key)) {
      final String overrideHash = configOverrides.get(key);
      return Optional.of(Hash.fromHexString(overrideHash));
    } else {
      return JsonUtil.getValueAsString(configRoot, key).map(Hash::fromHexString);
    }
  }
Instantiates a new Json genesis config options.

@param maybeConfig the optional config
@param configOverrides the config overrides map
@param transitionsConfig the transitions configuration
config/src/main/java/org/hyperledger/besu/config/JsonGenesisConfigOptions.java