添加服务器为客户缓存消息数量的配置

broker/src/main/java/io/moquette/BrokerConstants.java

@@ -115,6 +115,9 @@ public final class BrokerConstants {
     public static final String MESSAGE_ROAMING = "message.roaming";
     public static final String MESSAGE_Remote_History_Message = "message.remote_history_message";
 
+    public static final String MESSAGE_Max_Queue = "message.max_queue";
+
+
 
     private BrokerConstants() {
     }