SOLR-12947 created JsonQueryRequest to make using the JSON request API easier in SolrJ. SOLR-12965 is adding faceting support to this request object. This subtask of SOLR-12965 involves providing a way to parse the JSON faceting responses into easy-to-use SolrJ objects.
Currently the only option for users is to manipulate the underlying NamedList directly. We should create a "JsonFacetingResponse" in the model of ClusteringResponse, SuggesterResponse, TermsResponse, etc. and add an accessor to QueryResponse for getting at the faceting results.