docs: @Nullable
    public ServerSocketsList getServerSockets(long serverId, long fromId, int maxPageSize) {
      ServerSocketMap serverSockets = perServerSockets.get(serverId);
      if (serverSockets == null) {
        return null;
      }
      List<InternalWithLogId> socketList = new ArrayList<>(maxPageSize);
      Iterator<InternalInstrumented<SocketStats>> iterator
          = serverSockets.tailMap(fromId).values().iterator();
      while (socketList.size() < maxPageSize && iterator.hasNext()) {
        socketList.add(iterator.next());
      }
      return new ServerSocketsList(socketList, !iterator.hasNext());
    }