code: public FutureAPIResponse setUserAsFuture(String uid, Map<String, Object> properties,
        DateTime eventTime) throws IOException {
      return createEventAsFuture(new Event()
          .event("$set")
          .entityType("user")
          .entityId(uid)
          .eventTime(eventTime)
          .properties(properties));
    }
docs: Sends a set user properties request. Implicitly creates the user if it's not already there.
  Properties could be empty.
  
  @param uid ID of the user
  @param properties a map of all the properties to be associated with the user, could be empty
  @param eventTime timestamp of the event
  @return ID of this event