presto-main/src/main/java/io/prestosql/execution/scheduler/SplitPlacementResult.java/SplitPlacementResult/SplitPlacementResult
class SplitPlacementResult:    public SplitPlacementResult(ListenableFuture<?> blocked, Multimap<InternalNode, Split> assignments)
    {
        this.blocked = requireNonNull(blocked, "blocked is null");
        this.assignments = requireNonNull(assignments, "assignments is null");
    }