TaskSnapshot getTasksSnapshot() {
      TaskSnapshot result = new TaskSnapshot(tasks.size());
      for (Map.Entry<TezTaskAttemptID, Boolean> e : tasks.entrySet()) {
        result.attempts.add(e.getKey());
        result.guaranteed.add(new BooleanWritable(e.getValue()));
      }
      return result;
    }
@return A snapshot of the tasks running at this daemon from this AM.
Doesn't have to be consistent between multiple tasks; whether some task makes it into
a given heartbeat when it's about to be started/about to finish is a timing issue anyway.
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/AMReporter.java