code: public static String getTaskFailureExceptions(List<TaskState> taskStates) {
      StringBuffer sb = new StringBuffer();
  
      // Add task failure messages in a group followed by task failure exceptions
      appendTaskStateValues(taskStates, sb, TASK_FAILURE_MESSAGE_KEY);
      appendTaskStateValues(taskStates, sb, ConfigurationKeys.TASK_FAILURE_EXCEPTION_KEY);
  
      return sb.toString();
    }
docs: Get failure messages
  @return The concatenated failure messages from all the task states