public void processPubRec(Channel channel, MqttMessageIdVariableHeader variableHeader) {
MqttMessage pubRelMessage = MqttMessageFactory.newMessage(
new MqttFixedHeader(MqttMessageType.PUBREL, false, MqttQoS.AT_MOST_ONCE, false, 0),
MqttMessageIdVariableHeader.from(variableHeader.messageId()), null);
LOGGER.debug("PUBREC - clientId: {}, messageId: {}", (String) channel.attr(AttributeKey.valueOf("clientId")).get(), variableHeader.messageId());
dupPublishMessageStoreService.remove((String) channel.attr(AttributeKey.valueOf("clientId")).get(), variableHeader.messageId());
DupPubRelMessageStore dupPubRelMessageStore = new DupPubRelMessageStore().setClientId((String) channel.attr(AttributeKey.valueOf("clientId")).get())
.setMessageId(variableHeader.messageId());
dupPubRelMessageStoreService.put((String) channel.attr(AttributeKey.valueOf("clientId")).get(), dupPubRelMessageStore);
channel.writeAndFlush(pubRelMessage);
}