void closeReceivers(boolean beingSick) {
    synchronized (receivers) {
      for (Iterator<Connection> it = receivers.iterator(); it.hasNext();) {
        Connection con = it.next();
        if (!beingSick || con.getPreserveOrder()) {
          closeCon("Connection table being destroyed", con, beingSick);
          it.remove();
        }
      }
      // now close any sockets being formed
      synchronized (connectingSockets) {
        for (final Iterator<Map.Entry<Socket, ConnectingSocketInfo>> it =
            connectingSockets.entrySet().iterator(); it.hasNext();) {
          final Map.Entry<Socket, ?> entry = it.next();
          try {
            entry.getKey().close();
          } catch (IOException e) {
            // ignored - we're shutting down
          }
          it.remove();
        }
      }
    }
  }
Close all receiving threads. This is used during shutdown and is also used by a test hook that
makes us deaf to incoming messages.

@param beingSick a test hook to simulate a sick process
geode-core/src/main/java/org/apache/geode/internal/tcp/ConnectionTable.java