@Override
  public void clear() {
    for (int i = 1; i <= size; i++) {
      idToPos[posToId[i]] = NOT_PRESENT;
    }
    size = 0;
  }
@param elements the number of elements that can be stored in this heap. Currently the heap cannot be resized or
                shrunk/trimmed after initial creation. elements-1 is the maximum id that can be stored in this heap
planetiler-core/src/main/java/com/onthegomap/planetiler/collection/ArrayLongMinHeap.java