Removed outdated ant backwards compatibility marks

app/ant/processing/app/Schema.java

@@ -2,6 +2,9 @@ package processing.app;
 
 import processing.app.ui.Editor;
 
+// Stub class for backwards compatibility with the ant-build system
+// This class is not used in the Gradle build system
+// The actual implementation is in src/.../Schema.kt
 public class Schema {
     public static Editor handleSchema(String input, Base base) {
         return null;

app/ant/processing/app/contrib/ui/ContributionManagerKt.java

@@ -2,6 +2,9 @@ package processing.app.contrib.ui;
 
 import processing.app.contrib.ContributionManager;
 
+// Stub class for backwards compatibility with the ant-build system
+// This class is not used in the Gradle build system
+// The actual implementation is in src/.../ContributionManager.kt
 public final class ContributionManagerKt {
     public static void openContributionsManager() {
         ContributionManager.openLibraries();

app/build.gradle.kts

@@ -32,11 +32,9 @@ sourceSets{
     main{
         java{
             srcDirs("src")
-            exclude("**/*Kt.java")
         }
         kotlin{
             srcDirs("src")
-            exclude("**/*Kt.java")
         }
     }
 }