private boolean populateFromJoinedHeap(List<? super ExtendedCell> results,
    ScannerContext scannerContext) throws IOException {
    assert joinedContinuationRow != null;
    boolean moreValues =
      populateResult(results, this.joinedHeap, scannerContext, joinedContinuationRow);

    if (!scannerContext.checkAnyLimitReached(LimitScope.BETWEEN_CELLS)) {
      // We are done with this row, reset the continuation.
      joinedContinuationRow = null;
    }
    // As the data is obtained from two independent heaps, we need to
    // ensure that result list is sorted, because Result relies on that.
    ((List<Cell>) results).sort(comparator);
    return moreValues;
  }
Returns true if more cells exist after this batch, false if scanner is done
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionScannerImpl.java