@Override
      public Optional<ExtendedCell> getFirstKey() {
        if (splitPoint != null) {
          return Optional.of(ExtendedCellBuilderFactory.create(CellBuilderType.DEEP_COPY)
            .setType(Cell.Type.Put).setRow(splitPoint, 0, splitPoint.length - 1).build());
        } else {
          return Optional.empty();
        }
      }
A mock used so our tests don't deal with actual StoreFiles
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/MockHStoreFile.java