8294809: ListenerHelper for managing and disconnecting listeners

Reviewed-by: kcr, aghaisas

modules/javafx.controls/src/main/java/com/sun/javafx/scene/control/IDisconnectable.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+// Original code is re-licensed to Oracle by the author.
+// https://github.com/andy-goryachev/FxTextEditor/blob/master/src/goryachev/common/util/Disconnectable.java
+// Copyright © 2021-2022 Andy Goryachev <andy@goryachev.com>
+package com.sun.javafx.scene.control;
+
+/**
+ * A functional interface that provides a {@link #disconnect()} method.
+ */
+@FunctionalInterface
+public interface IDisconnectable {
+    /**
+     * Disconnects what has been connected. May be called multiple times, only the
+     * first invocation actually disconnects.
+     */
+    public void disconnect();
+}