private void readAll(Chunk chunk) {
        try (var iterator = chunk.newReader()) {
          while (iterator.hasNext()) {
            featuresToSort[i++] = iterator.next();
          }
        }
      }
A container for all features in a chunk read into memory for sorting.
planetiler-core/src/main/java/com/onthegomap/planetiler/collection/ExternalMergeSort.java