Initial commit

demo-app/src/main/java/com/example/leakdemo/Broadcaster.java

@@ -0,0 +1,23 @@
+package com.example.leakdemo;
+
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.function.Consumer;
+
+/** Classic Vaadin broadcaster. Fine by itself, leaks when listeners are never removed. */
+public final class Broadcaster {
+
+    private static final List<Consumer<String>> LISTENERS = new CopyOnWriteArrayList<>();
+
+    private Broadcaster() {
+    }
+
+    public static Runnable register(Consumer<String> listener) {
+        LISTENERS.add(listener);
+        return () -> LISTENERS.remove(listener);
+    }
+
+    public static void broadcast(String message) {
+        LISTENERS.forEach(l -> l.accept(message));
+    }
+}