code: public <T> RspList<T> castMessage(final Collection<Address> dests, Buffer data, RequestOptions opts) throws Exception {
          GroupRequest<T> req=cast(dests, data, opts, true);
          return req != null? req.getNow(null) : null;
      }
docs: Sends a message to all members and expects responses from members in dests (if non-null).
  @param dests A list of group members from which to expect responses (if the call is blocking).
  @param data The message to be sent
  @param opts A set of options that govern the call. See {@link org.jgroups.blocks.RequestOptions} for details
  @return RspList A list of Rsp elements, or null if the RPC is asynchronous
  @throws Exception If the request cannot be sent
  @since 2.9