code: public void sendEvent(final Map<String, String> params) {
          executor.execute(new Runnable() {
              @Override
              public void run() {
                  // put user id
                  params.put("cid", userId);
                  Multimap queryParams = HashMultimap.create();
                  for (Map.Entry<String, String> entry : params.entrySet()) {
                      String key = entry.getKey();
                      String value = entry.getValue();
                      Preconditions.checkNotNull(key, "Custom search param key must not be null.");
                      Preconditions.checkNotNull(value, "Custom search param value must not be null.");
                      queryParams.put(key, value);
                  }
                  viSearchHttpClient.get(ENDPOINT_SEND_ACTIONS, queryParams);
              }
          });
      }
docs: send event
  @param params