private static void handleDropOfferReq(SerializableDropOfferReq pack) {
		//List<String> sellers = pack.commandInfo;
		Server.loggerServer.info("[Server] drop auction");
		List<String> sellers = new ArrayList<String>();
		SelectionKey key;

		sellers.addAll(pack.commandInfo);
		// reset list in pack (no longer needed)
		pack.commandInfo = null;
		
		// send "drop offer" packet to each seller still logged in		
		for (String seller : sellers) {
			key = Server.registeredUsersChannels.get(seller);
			
			if (key == null) {
				Server.loggerServer.info("[Server] User " + seller + " is no longer" +
						" logged in => no 'drop offer' message sent to him");
				continue;
			}

			Server.loggerServer.info("[Server] sending drop offer announce to seller " + 
					seller + " (from buyer " + pack.userName + ", service " +
					pack.serviceName + ")");

			Server.sendData(key, pack);
		}
	}