         - Parameter callback:
      */
     public func listGroups(_ callback: @escaping (String, String) -> ()) {
-        for (_, broker) in _brokers {
+        for (_, broker) in brokers {
             dispatchQueue.async {
                 broker.listGroups() { a, b in
                     callback(a, b)

    }
    
    func getGroupCoordinator(groupId: String, callback: @escaping (Broker) -> Void) {
        _brokers.first?.value.getGroupCoordinator(groupId: groupId) { response in
            let host = response.host
            let port = response.port
            

        ) {
        var dispatchBlocks = [()->()]()
        
        for (_, broker) in brokers {
            let dispatchBlock = DispatchWorkItem(qos: .unspecified, flags: []) {
                
                var handleGetTopicMetadata: ((MetadataResponse) -> Void)!
