function findLowUtilizationRegion(startIndex, stopIndex)
        {
            var /** @const */ threshold = 0.1;
            var cutIndex = startIndex;
            var cutTime = (tasks[cutIndex].startTime() + tasks[cutIndex].endTime()) / 2;
            var usedTime = 0;
            var step = Math.sign(stopIndex - startIndex);
            for (var i = startIndex; i !== stopIndex; i += step) {
                var task = tasks[i];
                var taskTime = (task.startTime() + task.endTime()) / 2;
                var interval = Math.abs(cutTime - taskTime);
                if (usedTime < threshold * interval) {
                    cutIndex = i;
                    cutTime = taskTime;
                    usedTime = 0;
                }
                usedTime += task.endTime() - task.startTime();
            }
            return cutIndex;
        }
@param {number} startIndex
@param {number} stopIndex
@return {number}