This pull request introduces an optimization to the containsAll method in collection handling. It is aim to improve the method's performance, especially when dealing with large collections.

Previously, the containsAll method used this.backingList.containsAll(c), iterating over each element in the collection c and checking for its presence in this.backingList. This approach, while straightforward, can lead to suboptimal performance for large collections due to the potential for repeated linear searches.

This change has 2 benefits: - Improved Performance: This change significantly reduces the computational complexity of the containsAll method, especially beneficial when this.backingList and c are large. - Scalability: As the size of the collections grows, the performance benefits of this optimization become even more pronounced, making collection handling more scalable.

Comment From: jhoeller

In general, we don't apply such optimizations in our own collection adapters. Such a HashSet-based access pattern is better off in the caller where the Set adapter can possibly be reused for several operations etc. Decorators from an outer List to an inner List are not really meant to optimize that behavior.

From a caller's perspective, AutoPopulatingList is an arbitrary List: so when the caller performs a containsAll call on it, standard List performance characteristics are expected. A caller might even apply a HashSet-based access pattern already, leading to inefficient double wrapping when we internally do it as well.