docs: public static boolean getCatalogIndexExpressions(Index index, StmtTableScan tableScan,
              List<AbstractExpression> indexedExprs, List<ColumnRef> indexedColRefs) {
          String exprsjson = index.getExpressionsjson();
          if (exprsjson.isEmpty()) {
              CatalogUtil.getSortedCatalogItems(index.getColumns(), "index", indexedColRefs);
          } else {
              try {
                  AbstractExpression.fromJSONArrayString(exprsjson, tableScan, indexedExprs);
              } catch (JSONException e) {
                  e.printStackTrace();
                  assert(false);
              }
          }
          return exprsjson.isEmpty();
      }