private void checkParentIdIsValid(final int parentId) throws IndexOutOfBoundsException {
      final int recordsAllocatedSoFar = allocatedRecordsCount.get();
      if (!(NULL_ID <= parentId && parentId <= recordsAllocatedSoFar)) {
        throw new IndexOutOfBoundsException(
          "parentId(=" + parentId + ") is outside of allocated IDs range [0, " + recordsAllocatedSoFar + "]");
      }
    }
private void checkParentIdIsValid(final int parentId)