A `terms` agg with an `exclude` arrray of medium size (in my case, 86 strings) was sufficient to cause this error:
```
Caused by: org.apache.lucene.util.automaton.TooComplexToDeterminizeException: De…
Develop the User-based Collaborative Filtering Recommender using KNN Nearest Neighbor.
Put the references here:
Herlocker, J., Konstan, J., Borchers, A., & Riedl, J.. An algorithmic framework for pe…