private Request buildRequestRecursive(Target<TranscodeType> target, ThumbnailRequestCoordinator parentCoordinator) {
        if (thumbnailRequestBuilder != null) {
            if (isThumbnailBuilt) {
                throw new IllegalStateException("You cannot use a request as both the main request and a thumbnail, "
                        + "consider using clone() on the request(s) passed to thumbnail()");
            }
            // Recursive case: contains a potentially recursive thumbnail request builder.
            if (thumbnailRequestBuilder.animationFactory.equals(NoAnimation.getFactory())) {
                thumbnailRequestBuilder.animationFactory = animationFactory;
            }

            if (thumbnailRequestBuilder.priority == null) {
                thumbnailRequestBuilder.priority = getThumbnailPriority();
            }

            if (Util.isValidDimensions(overrideWidth, overrideHeight)
                    && !Util.isValidDimensions(thumbnailRequestBuilder.overrideWidth,
                            thumbnailRequestBuilder.overrideHeight)) {
              thumbnailRequestBuilder.override(overrideWidth, overrideHeight);
            }

            ThumbnailRequestCoordinator coordinator = new ThumbnailRequestCoordinator(parentCoordinator);
            Request fullRequest = obtainRequest(target, sizeMultiplier, priority, coordinator);
            // Guard against infinite recursion.
            isThumbnailBuilt = true;
            // Recursively generate thumbnail requests.
            Request thumbRequest = thumbnailRequestBuilder.buildRequestRecursive(target, coordinator);
            isThumbnailBuilt = false;
            coordinator.setRequests(fullRequest, thumbRequest);
            return coordinator;
        } else if (thumbSizeMultiplier != null) {
            // Base case: thumbnail multiplier generates a thumbnail request, but cannot recurse.
            ThumbnailRequestCoordinator coordinator = new ThumbnailRequestCoordinator(parentCoordinator);
            Request fullRequest = obtainRequest(target, sizeMultiplier, priority, coordinator);
            Request thumbnailRequest = obtainRequest(target, thumbSizeMultiplier, getThumbnailPriority(), coordinator);
            coordinator.setRequests(fullRequest, thumbnailRequest);
            return coordinator;
        } else {
            // Base case: no thumbnail.
            return obtainRequest(target, sizeMultiplier, priority, parentCoordinator);
        }
    }
Preloads the resource into the cache using {@link Target#SIZE_ORIGINAL} as the target width and height.
Equivalent to calling {@link #preload(int, int)} with {@link Target#SIZE_ORIGINAL} as the width and height.

@see #preload(int, int)

@return A {@link Target} that can be used to cancel the load via
       {@link Glide#clear(Target)}.
core/src/main/java/com/bumptech/glide/GenericRequestBuilder.java