matchmakerData property
Information about the matchmaking process that was used to create the game session. It is in JSON syntax, formatted as a string. In addition the matchmaking configuration used, it contains data on all players assigned to the match, including player attributes and team assignments. For more details on matchmaker data, see Match Data. Matchmaker data is useful when requesting match backfills, and is updated whenever new players are added during a successful backfill (see StartMatchBackfill).
Implementation
final String? matchmakerData;