presto-main/src/main/java/io/prestosql/execution/executor/TaskHandle.java/TaskHandle/TaskHandle
class TaskHandle:    public TaskHandle(
            TaskId taskId,
            MultilevelSplitQueue splitQueue,
            DoubleSupplier utilizationSupplier,
            int initialSplitConcurrency,
            Duration splitConcurrencyAdjustFrequency,
            OptionalInt maxDriversPerTask)
    {
        this.taskId = requireNonNull(taskId, "taskId is null");
        this.splitQueue = requireNonNull(splitQueue, "splitQueue is null");
        this.utilizationSupplier = requireNonNull(utilizationSupplier, "utilizationSupplier is null");
        this.maxDriversPerTask = requireNonNull(maxDriversPerTask, "maxDriversPerTask is null");
        this.concurrencyController = new SplitConcurrencyController(
                initialSplitConcurrency,
                requireNonNull(splitConcurrencyAdjustFrequency, "splitConcurrencyAdjustFrequency is null"));
    }