// cf (tweeter -> followers) ==> emit(url, follower)
ValuelessColumnsMapper followersColumnsMapper = new ValuelessColumnsMapper("url", "follower", true);
CassandraLookupBolt<String, String, String> followersBolt = new CassandraLookupBolt<String, String, String>(configKey,
followersTupleMapper, followersColumnsMapper);
builder.addBolt(new InitBolt());
builder.addBolt(tweetersBolt).shuffleGrouping();
builder.addBolt(followersBolt).shuffleGrouping();
builder.addBolt(new PartialUniquer()).fieldsGrouping(new Fields("id", "follower"));
builder.addBolt(new CountAggregator()).fieldsGrouping(new Fields("id"));