code: void registerTaskStarted(Task task) {
          synchronized (m_activeTasks) {
              String mapKey = createMapKey(task.getTenant(), task.getTaskID());
              if (m_activeTasks.put(mapKey, task) != null) {
                  m_logger.warn("Task {} registered as started but was already running", mapKey);
              }
          }
      }
docs: Called by a Task when it's thread starts. This lets the task manager know
  which tasks are its own.
  
  @param task  {@link Task} that is executing task.