Allow namespacing of ElasticSearch indices. Pre 12 you could set the index on the search service thus:
This allowed you to share an ES cluster between multiple Sakai instances, one index for each Sakai instance. Now, however, you can't. You need to set the index name on your particular index builder. So, you'd have to set an indexName on the main sakai index, and on the questions index used by Samigo. As we add more tool specfic indices we'd need to set the index names for each one in properties, for each of our Sakai instances.
Rather than do that, it makes more sense to have a namepace, so 'instance1_sakai_index' and 'instance1_questions_index'. DRYer and still keeps things tidy in ES.