presto-main/src/main/java/io/prestosql/execution/scheduler/SqlQueryScheduler.java/SqlQueryScheduler/getBasicStageStats
class SqlQueryScheduler:    public BasicStageStats getBasicStageStats()
    {
        List<BasicStageStats> stageStats = stages.values().stream()
                .map(SqlStageExecution::getBasicStageStats)
                .collect(toImmutableList());

        return aggregateBasicStageStats(stageStats);
    }