public List<Task<?>> getDependentTasks() {
    return getChildTasks();
  }
The default dependent tasks are just child tasks, but different types could implement their own
(e.g. ConditionalTask will use the listTasks as dependents).

@return a list of tasks that are dependent on this task.
ql/src/java/org/apache/hadoop/hive/ql/exec/Task.java