fix(cluster): change HazelcastMsg payload to byte[]

broker/src/main/java/io/moquette/interception/HazelcastMsg.java

@@ -10,13 +10,13 @@ public class HazelcastMsg implements Serializable{
     private final String clientId;
     private final String userName;
     private final byte qos;
-    private final String payload;
+    private final byte[] payload;
     private final String topic;
 
     public HazelcastMsg(String clientId, String topic , byte qos, byte[] payload, String userName) {
         this.clientId = clientId;
         this.qos = qos;
-        this.payload = new String(payload);
+        this.payload = payload;
         this.userName = userName;
         this.topic = topic;
     }
@@ -30,7 +30,7 @@ public class HazelcastMsg implements Serializable{
         return qos;
     }
 
-    public String getPayload() {
+    public byte[] getPayload() {
         return payload;
     }