@Override
  public boolean processMappings(@NotNull KeyValueProcessor processor) throws IOException {
    doFlush();

    if (hasZeroKey) {
      if (!processor.process(0, zeroKeyValue)) return false;
    }

    if (root.address == UNDEFINED_ADDRESS) return true;
    root.syncWithStore();

    return processLeafPages(root.getNodeView(), processor);
  }
@Override
  public boolean processMappings(@NotNull KeyValueProcessor processor)