Polish

See gh-43876

Signed-off-by: arefbehboudi <behboodiaref@gmail.com>

buildSrc/src/main/java/org/springframework/boot/build/antora/Extensions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -84,7 +84,7 @@ public final class Extensions {
 
 	static final class AntoraExtensionsConfiguration {
 
-		private Map<String, Map<String, Object>> extensions = new TreeMap<>();
+		private final Map<String, Map<String, Object>> extensions = new TreeMap<>();
 
 		private AntoraExtensionsConfiguration(List<String> names) {
 			names.forEach((name) -> this.extensions.put(name, null));

buildSrc/src/main/java/org/springframework/boot/build/bom/BomExtension.java

@@ -617,9 +617,9 @@ public class BomExtension {
 
 	public static final class GitHub {
 
-		private String organization;
+		private final String organization;
 
-		private String repository;
+		private final String repository;
 
 		private final List<String> issueLabels;