Generated $Route classes as final (#524)

These can be final right?

Co-authored-by: Josiah Noel <32279667+SentryMan@users.noreply.github.com>

Author: rbygrave

http-generator-helidon/src/main/java/io/avaje/http/generator/helidon/nima/ControllerWriter.java

@@ -123,7 +123,7 @@ private void writeRoutes(List<ControllerMethodWriter> methods) {
   private void writeClassStart() {
     writer.append(AT_GENERATED).eol();
     writer.append(diAnnotation()).eol();
-    writer.append("public class %s$Route implements HttpFeature {", shortName).eol().eol();
+    writer.append("public final class %s$Route implements HttpFeature {", shortName).eol().eol();
 
     var controllerName = "controller";
     var controllerType = shortName;

http-generator-javalin/src/main/java/io/avaje/http/generator/javalin/ControllerWriter.java

@@ -84,7 +84,7 @@ private void writeClassStart() {
     writer.append(AT_GENERATED).eol();
     writer.append(diAnnotation()).eol();
     writer
-      .append("public class ")
+      .append("public final class ")
       .append(shortName)
       .append(javalin6 ? "$Route extends AvajeJavalinPlugin {" : "$Route implements Plugin {")
       .eol()

http-generator-jex/src/main/java/io/avaje/http/generator/jex/ControllerWriter.java

@@ -89,7 +89,7 @@ private void writeRouting(MethodReader method) {
   private void writeClassStart() {
     writer.append(AT_GENERATED).eol();
     writer.append(diAnnotation()).eol();
-    writer.append("public class ").append(shortName).append("$Route implements Routing.HttpService {").eol().eol();
+    writer.append("public final class ").append(shortName).append("$Route implements Routing.HttpService {").eol().eol();
 
     String controllerName = "controller";
     String controllerType = shortName;