refactoring

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

@@ -84,8 +84,7 @@ public class MessageBuilder {
   /**
    * Fails the MessageBuilder if the message is empty.
    * if this fails, all subsequent calls to that MessageBuilder will do nothing
-   *
-   * @return an EmptyMessageBuilder if the message is empty, itself otherwise
+   * @return a NullMessageBuilder if the message is empty, itself otherwise
    */
   public MessageBuilder failIfEmpty() {
     return failIf(message.isEmpty());
@@ -93,7 +92,7 @@ public class MessageBuilder {
 
   public MessageBuilder failIf(boolean value) {
     if (value) {
-      return new EmptyMessageBuilder();
+      return new NullMessageBuilder();
     } else {
       return this;
     }

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

@@ -2,13 +2,13 @@ package sh.okx.rankup.messages;
 
 import org.bukkit.command.CommandSender;
 
-public class EmptyMessageBuilder extends MessageBuilder {
-  EmptyMessageBuilder() {
+public class NullMessageBuilder extends MessageBuilder {
+  NullMessageBuilder() {
     super(null);
   }
 
   @Override
-  public MessageBuilder failIfEmpty() {
+  public MessageBuilder failIf(boolean value) {
     return this;
   }