private KeyValueStorage constructKeyValueStorage(
      @Named("KeyValueStorageName") final String keyValueStorageName,
      final BesuConfiguration commonConfiguration,
      final MetricsSystem metricsSystem,
      final SegmentIdentifier segment) {

    switch (keyValueStorageName) {
      case "rocksdb":
        return rocksDBFactory.get().create(segment, commonConfiguration, metricsSystem);
      default:
        System.err.println("Unknown key, continuing as though 'memory' was specified");
      // fall through
      case "memory":
        return new InMemoryKeyValueStorage();
    }
  }
Default constructor for the DataStoreModule class.
ethereum/evmtool/src/main/java/org/hyperledger/besu/evmtool/DataStoreModule.java