code: public void loadSession(final String sessionId, final Handler<Object> handler) {
          if (sessionId == null) {
              handler.handle(null);
              return;
          }
  
          store.get(sessionId, new Handler<JsonObject>() {
              @Override
              public void handle(JsonObject session) {
                  if (session != null) {
                      put("session", session);
                  }
  
                  response().headersHandler(new Handler<Void>() {
                      @Override
                      public void handle(Void event) {
                          int responseStatus = response().getStatusCode();
                          // Only save on success and redirect status codes
                          if (responseStatus >= 200 && responseStatus < 400) {
                          	JsonObject session = get("session");
                              if (session != null) {
                                  store.set(sessionId, session, new Handler<Object>() {
                                      @Override
                                      public void handle(Object error) {
                                          if (error != null) {
                                              // TODO: better handling of errors
                                              System.err.println(error);
                                          }
                                      }
                                  });
                              }
                          }
                      }
                  });
  
                  handler.handle(null);
              }
          });
      }
docs: Loads a session given its session id and sets the "session" property in the request context.
  @param sessionId the id to load
  @param handler the success/complete handler