anchor.diff:  
   === group.invite.request
   Creator of a group can invite other users
  -[source,json]
  +[source]
   {
       "id": "7686d130-2223-4769-ab9f-5cebcf795e80",
       "userId": "7686d130-2223-4769-ab9f-5cebcf795e80"
  
positive.code: === group.invite.response
  
  === group.invited
  [source,json]
  {
      "id": "7686d130-2223-4769-ab9f-5cebcf795e80"
  }
  
negative.code: === group.poker.start.response
  
  === group.poker.bet.request
  [source]
  {
      "id": "7686d130-2223-4769-ab9f-5cebcf795e80",
      "bet": 13 // allowed values: -1, 0.5, 1, 2, 3, 5, 8, 13, 20, 30, 40, 100
  