private void addIgnoredCallback(ResourceCallback cb) {
        if (ignoredCallbacks == null) {
            ignoredCallbacks = new HashSet<ResourceCallback>();
        }
        ignoredCallbacks.add(cb);
    }
A class that manages a load by adding and removing callbacks for for the load and notifying callbacks when the
load completes.
core/src/main/java/com/bumptech/glide/load/engine/EngineJob.java