void throwIfClosed() {
    if (closed.get()) {
      LOG.error("Attempting to use a closed RocksDbKeyValueStorage");
      throw new IllegalStateException("Storage has been closed");
    }
  }
Safe method to map segment identifier to column handle.

@param segment segment identifier
@return column handle
plugins/rocksdb/src/main/java/org/hyperledger/besu/plugin/services/storage/rocksdb/segmented/RocksDBColumnarKeyValueStorage.java