code: private List<Transformation> getTransformations() {
      if (transformations == null) {
        transformations = new LinkedList<Transformation>();
        if (useCircularTransformation) {
          transformations.add(new CircleTransformation());
        }
      }
      return transformations;
    }
docs: Lazy instantiation of the list of transformations used during the image download. This method
  returns a List<Transformation> because Picasso doesn't support a null instance as
  transformation.