add autorankup - closes #2

src/main/java/sh/okx/rankup/messages/EmptyMessageBuilder.java

@@ -7,12 +7,9 @@ class EmptyMessageBuilder extends MessageBuilder {
     super(null);
   }
 
-  /**
-   * what are you doing failing if empty when it has already failed?
-   */
   @Override
   public MessageBuilder failIfEmpty() {
-    throw new UnsupportedOperationException();
+    return this;
   }
 
   @Override