@Override
    public void onRequestSuccess(Request request) {
        if (request.equals(thumb)) {
            return;
        }
        if (coordinator != null) {
            coordinator.onRequestSuccess(this);
        }
        // Clearing the thumb is not necessarily safe if the thumb is being displayed in the Target,
        // as a layer in a cross fade for example. The only way we know the thumb is not being
        // displayed and is therefore safe to clear is if the thumb request has not yet completed.
        if (!thumb.isComplete()) {
          thumb.clear();
        }
    }
Returns true if the request is the request loading the fullsize image and if neither the full nor the thumbnail
image have completed sucessfully.

@param request {@inheritDoc}.
core/src/main/java/com/bumptech/glide/request/ThumbnailRequestCoordinator.java