def canonical_before_model_callbacks(
      self,
  ) -> list[_SingleBeforeModelCallback]:
    """The resolved self.before_model_callback field as a list of _SingleBeforeModelCallback.

    This method is only for use by Agent Development Kit.
    """
    if not self.before_model_callback:
      return []
    if isinstance(self.before_model_callback, list):
      return self.before_model_callback
    return [self.before_model_callback]
The resolved self.before_model_callback field as a list of _SingleBeforeModelCallback.

    This method is only for use by Agent Development Kit.
    
src/google/adk/agents/llm_agent.py