Sets a property value.
$property_name: The name of the property to set; e.g., 'title' or 'name'.
$value: The value to set, or NULL to unset the property.
bool $notify: (optional) Whether to notify the parent object of the change. Defaults to TRUE. If the update stems from a parent object, set it to FALSE to avoid being notified again.
\Drupal\Core\TypedData\TypedDataInterface The property object.
\InvalidArgumentException If the specified property does not exist.
public function set($property_name, $value, $notify = TRUE);