List<Task<?>> getTasks()  {
      return tasks;
    }
This class encapsulate all {@link Task} required to be copied.
This is required because {@link FetchTask} list of {@link Task} may hold reference to same
objects (e.g. list of result files) and are required to be serialized/de-serialized together.
ql/src/java/org/apache/hadoop/hive/ql/parse/ExecuteStatementAnalyzer.java