code: private static void updatePartialIndex(IndexScanPlanNode scan) {
          if (scan.getPredicate() == null && scan.getPartialIndexPredicate() != null) {
              if (scan.isForSortOrderOnly()) {
                  scan.setPredicate(Collections.singletonList(scan.getPartialIndexPredicate()));
              }
              scan.setForPartialIndexOnly();
          }
      }
docs: Check if the index for the scan node is a partial index, and if so, make sure that the
  scan contains index predicate, and update index reason as needed for @Explain.
  @param scan index scan plan node