code: @SuppressWarnings("unchecked")
      public ApiBuddy execute() {
          User sfsOwner = api.getUserByName(owner);
          ApiUser targetUser = getUser(target);
          ApiUser ownerUser = (ApiUser) sfsOwner.getProperty(APIKey.USER);
          ISFSBuddyResponseApi responseAPI = SmartFoxServer.getInstance().getAPIManager()
                  .getBuddyApi().getResponseAPI();
          ISFSEventManager eventManager = SmartFoxServer.getInstance().getEventManager();
          BuddyList buddyList = sfsOwner.getZone()
                  .getBuddyListManager().getBuddyList(owner);
          BuddyListManager buddyListManager = sfsOwner.getZone().getBuddyListManager();
          checkBuddyManagerIsActive(buddyListManager, sfsOwner);
          sfsOwner.updateLastRequestTime();
          ApiBuddyImpl buddy = new ApiBuddyImpl(target, temp);
          buddy.setOwner(ownerUser);
          buddy.setParentBuddyList(buddyList);
          if(targetUser != null)  buddy.setUser(targetUser);
          try {
              buddyList.addBuddy(buddy);
              if (fireClientEvent)
                  responseAPI.notifyAddBuddy(buddy, sfsOwner);
              if (fireServerEvent) {
                  Map<ISFSEventParam, Object> evtParams = new HashMap<>();
                  evtParams.put(SFSEventParam.ZONE, sfsOwner.getZone());
                  evtParams.put(SFSEventParam.USER, sfsOwner);
                  evtParams.put(SFSBuddyEventParam.BUDDY, buddy);
                  eventManager.dispatchEvent(new SFSEvent(SFSEventType.BUDDY_ADD, evtParams));
              }
          } catch (SFSBuddyListException e) {
              if (fireClientEvent) {
                  api.getResponseAPI().notifyRequestError(e, sfsOwner, SystemRequest.AddBuddy);
              }
              return null;
          }
          return buddy;
      }
docs: Execute to add a buddy to list