MessageHolder(String routingKey, Message message, Map queueNameToNodeIdMap) { this.routingKey = routingKey;  this.message = message;  this.queueNameToNodeIdMap = queueNameToNodeIdMap;
public MessageHolder() {
   MessageHolder(String routingKey, Message message, Map queueNameToNodeIdMap)   {      this.routingKey = routingKey;            this.message = message;            this.queueNameToNodeIdMap = queueNameToNodeIdMap;   }