docs: def _properties_model_to_dict(properties):
      """
      Convert properties model to dict.
  
      Args:
          properties: Properties model.
  
      Returns:
          dict: Converted model.
      """
      result = {}
      for attr in properties.__dict__:
          value = getattr(properties, attr)
  
          if hasattr(value, '__module__') and 'models' in value.__module__:
              value = _properties_model_to_dict(value)
  
          if not (value is None or (isinstance(value, dict) and not value)):
              result[attr] = value
  
      return result