presto-main/src/main/java/io/prestosql/cost/JoinStatsRule.java/JoinStatsRule/crossJoinStats
class JoinStatsRule:    private PlanNodeStatsEstimate crossJoinStats(JoinNode node, PlanNodeStatsEstimate leftStats, PlanNodeStatsEstimate rightStats, TypeProvider types)
    {
        PlanNodeStatsEstimate.Builder builder = PlanNodeStatsEstimate.builder()
                .setOutputRowCount(leftStats.getOutputRowCount() * rightStats.getOutputRowCount());

        node.getLeft().getOutputSymbols().forEach(symbol -> builder.addSymbolStatistics(symbol, leftStats.getSymbolStatistics(symbol)));
        node.getRight().getOutputSymbols().forEach(symbol -> builder.addSymbolStatistics(symbol, rightStats.getSymbolStatistics(symbol)));

        return normalizer.normalize(builder.build(), types);
    }