public GifRequestBuilder<ModelType> thumbnail(GifRequestBuilder<?> thumbnailRequest) {
        super.thumbnail(thumbnailRequest);
        return this;
    }
Loads and displays the GIF retrieved by the given thumbnail request if it finishes before this
request. Best used for loading thumbnail GIFs that are smaller and will be loaded more quickly
than the fullsize GIF. There are no guarantees about the order in which the requests will actually
finish. However, if the thumb request completes after the full request, the thumb GIF will never
replace the full image.

@see #thumbnail(float)

<p>
    Note - Any options on the main request will not be passed on to the thumbnail request. For example, if
    you want an animation to occur when either the full GIF loads or the thumbnail loads,
    you need to call {@link #animate(int)} on both the thumb and the full request. For a simpler thumbnail
    option where these options are applied to the humbnail as well, see {@link #thumbnail(float)}.
</p>

<p>
    Only the thumbnail call on the main request will be obeyed, recursive calls to this method are ignored.
</p>

@param thumbnailRequest The request to use to load the thumbnail.
@return This builder object.
core/src/main/java/com/bumptech/glide/GifRequestBuilder.java