presto-main/src/main/java/io/prestosql/execution/SqlQueryExecution.java/SqlQueryExecution/PlanRoot
class SqlQueryExecution:        public PlanRoot(SubPlan root, boolean summarizeTaskInfos, Multimap<CatalogName, ConnectorTableHandle> tableHandles)
        {
            this.root = requireNonNull(root, "root is null");
            this.summarizeTaskInfos = summarizeTaskInfos;
            this.tableHandles = ImmutableMultimap.copyOf(requireNonNull(tableHandles, "tableHandles is null"));
        }