presto-main/src/main/java/io/prestosql/cost/PlanNodeStatsEstimate.java/PlanNodeStatsEstimate/PlanNodeStatsEstimate
class PlanNodeStatsEstimate:    private PlanNodeStatsEstimate(double outputRowCount, PMap<Symbol, SymbolStatsEstimate> symbolStatistics)
    {
        checkArgument(isNaN(outputRowCount) || outputRowCount >= 0, "outputRowCount cannot be negative");
        this.outputRowCount = outputRowCount;
        this.symbolStatistics = symbolStatistics;
    }