Place a group call

1. Use the spark.rooms().create() API to create a Room.

   spark.rooms().create("hello world",null,(result) -> {
           if (result.isSuccessful()) {
               Room r  = result.getData();
               //....
           } else {
               //....
           }
       });

2. Use the spark.memberships().create() API to add people to the Room.

   spark.memberships().create(roomId,null,personEmail,true, (result) -> {
           if (result.isSuccessful()) {
             //....
           } else {
             //....
           }
       });

3. Dial a room by room id to make a group call with all peoples in the room.

   spark.phone().dial(roomId, MediaOption. audioVideoSharing(new Pair<>(localView,remoteView),shareView), (result) -> {
           if (result.isSuccessful()) {
               call = result.getData();
               call.setObserver(callObserver);
           }
           //...
       });

4. In order to get the event of a participant in the call, the callback function onCallMembershipChanged is used.

   @Override
   public void onCallMembershipChanged(CallMembershipChangedEvent callMembershipChangeEvent) {
       CallMembership membership = callMembershipChangeEvent.getCallMembership();
       if (callMembershipChangeEvent instanceof MembershipJoinedEvent) {
           Ln.d("The " + membership.getEmail() + " accept the call and joins to the Room");
       } else if (callMembershipChangeEvent instanceof MembershipLeftEvent) {
           Ln.d("The " + membership.getEmail() + " hangup the call and leaves to the Room");
       } else if (callMembershipChangeEvent instanceof MembershipDeclinedEvent) {
           Ln.d("The " + membership.getEmail() + " decline the call");
       } else if (callMembershipChangeEvent instanceof MembershipSendingVideoEvent) {
           Ln.d("The " + membership.getEmail() + (membership.isSendingVideo() ? " unmute ":" mute " ) + " video");
       } else if (callMembershipChangeEvent instanceof MembershipSendingAudioEvent) {
           Ln.d("The " + membership.getEmail() + (membership.isSendingAudio() ? " unmute ":" mute " ) + " voice");
       } else if (callMembershipChangeEvent instanceof MembershipSendingSharingEvent) {
           Ln.d("The " + membership.getEmail() + (membership.isSendingSharing() ? " start ":" stop " ) + " sharing");
       }
   }