AsyncResultSet.java

                // how we did async in the dark ages
                Futures.addCallback(session.executeAsync(boundStatement), new FutureCallback<ResultSet>() {
                    @Override 
                    public void onSuccess(ResultSet rows) {
                        rows.forEach(row -> mappings.put(row.getString(0), row.getString(1)));
                    }

                    @Override 
                    public void onFailure(Throwable throwable) {
                        // handle failure
                    }
                });