Added empty constructor

src/main/java/Main/ProtocolMessage.java

@@ -62,6 +62,9 @@ public class ProtocolMessage {
         System.arraycopy(message, 0, this.raw, 4, message.length);
     }
 
+    public ProtocolMessage() {
+    }
+
     public ProtocolMessage(String message) {
         this.length = message.length();
         this.message = message.toCharArray();