public boolean isConnected() {
        if (this.size() < 2) {
            return true;
        }
        
        final Iterator<T> iterator = this.iterator();
        final T source = iterator.next();
        
        Deque<T> queue = new LinkedList<>();
        Set<T> visited = new HashSet<T>();
        
        queue.addLast(source);
        visited.add(source);
        
        while (queue.isEmpty() == false) {
            final T current = queue.removeFirst();
            
            for (final T child : current) {
                if (visited.contains(child) == false) {
                    visited.add(child);
                    queue.addLast(child);
                }
            }
        }
        
        if (visited.size() != this.size()) {
            return false;
        }
        
        for (final T node : visited) {
            if (this.containsNode(node) == false) {
                return false;
            }
        }
        
        for (final T node : this) {
            if (visited.contains(node) == false) {
                return false;
            }
        }
        
        return true;
    }