@Override
  public void clear(final SegmentIdentifier segmentIdentifier) {
    Optional.ofNullable(columnHandlesBySegmentIdentifier.get(segmentIdentifier))
        .ifPresent(RocksDbSegmentIdentifier::reset);
  }
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