@Override
    public String getId() {
        if (id == null) {
            StringBuilder sb = new StringBuilder();
            for (Transformation<T> transformation : transformations) {
                sb.append(transformation.getId());
            }
            id = sb.toString();
        }
        return id;
    }
A transformation that applies one or more transformations in iteration order to a resource.

@param <T> The type of {@link Resource} that will be transformed.
core/src/main/java/com/bumptech/glide/load/MultiTransformation.java