Begin implementation of CheckStyle style checking

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/help/HelpMap.java

@@ -10,7 +10,7 @@ import java.util.List;
  * The HelpMap tracks all help topics registered in a Bukkit server. When the
  * server starts up or is reloaded, help is processed and topics are added in
  * the following order:
- * 
+ *
  * <ol>
  * <li>General topics are loaded from the help.yml
  * <li>Plugins load and optionally call {@code addTopic()}
@@ -37,7 +37,7 @@ public interface HelpMap {
      */
     @NotNull
     public Collection<HelpTopic> getHelpTopics();
-    
+
     /**
      * Adds a topic to the server's help index.
      *

paper-api/src/main/java/org/bukkit/help/HelpTopicComparator.java

@@ -10,7 +10,7 @@ import java.util.Comparator;
  * All topics are listed in alphabetic order, but topics that start with a
  * slash come after topics that don't.
  */
-public class HelpTopicComparator implements Comparator<HelpTopic> {
+public final class HelpTopicComparator implements Comparator<HelpTopic> {
 
     // Singleton implementations
     private static final TopicNameComparator tnc = new TopicNameComparator();
@@ -31,7 +31,7 @@ public class HelpTopicComparator implements Comparator<HelpTopic> {
         return tnc.compare(lhs.getName(), rhs.getName());
     }
 
-    public static class TopicNameComparator implements Comparator<String> {
+    public static final class TopicNameComparator implements Comparator<String> {
         private TopicNameComparator(){}
 
         public int compare(@NotNull String lhs, @NotNull String rhs) {