@Override public Call<T> map(AsyncResultSet rs) {
    return new AccumulateNextResults<>(
      supplier().get(),
      accumulator(),
      finisher()
    ).map(rs);
  }
Customizes the aggregated result. For example, summarizing or making immutable.
zipkin-storage/cassandra/src/main/java/zipkin2/storage/cassandra/internal/call/AccumulateAllResults.java