code: def process_result_of_unknown_task(
      self,
      client: Client,
      task_name: str,
      client_task_id: str,
      result: Shareable,
      fl_ctx: FLContext,
  ):
      self.log_warning(
          fl_ctx,
          f"Unknown task: {task_name} from client {client.name}.",
      )
  
file_path: xgboost/demo/nvflare/horizontal/custom/controller.py
imports: import multiprocessing
  from nvflare.apis.client import Client
  from nvflare.apis.fl_context import FLContext
  from nvflare.apis.impl.controller import Controller, Task
  from nvflare.apis.shareable import Shareable
  from nvflare.apis.signal import Signal
  from trainer import SupportedTasks
  import xgboost.federated
label_desc: Use image node_id 4 for calling the XGBoostController obj's underlying member method code with example usage: obj.process_result_of_unknown_task(client, task_name, client_task_id, result, fl_ctx) without return types