public @NotNull PersistentHashMapStatistics getStatistics() throws IOException {
    long valueStorageSizeInBytes = myValueStorage == null ? -1 : myValueStorage.getSize();
    return new PersistentHashMapStatistics(((PersistentBTreeEnumerator<?>)myEnumerator).getStatistics(), valueStorageSizeInBytes);
  }
public @NotNull PersistentHashMapStatistics getStatistics()