--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/jdk/internal/PreviewFeature.java	Mon Oct 21 15:38:26 2019 +0200
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2019, 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.
+ */
+
+package jdk.internal;
+
+import java.lang.annotation.*;
+
+/**
+ * Indicates the API declaration in question is associated with a
+ * <em>preview feature</em>. See JEP 12: "Preview Language and VM
+ * Features" (http://openjdk.java.net/jeps/12).
+ * @since 14
+ */
+// Match the meaningful targets of java.lang.Deprecated, omit local
+// variables and parameter declarations
+@Target({ElementType.METHOD,
+         ElementType.CONSTRUCTOR,
+         ElementType.FIELD,
+         ElementType.PACKAGE,
+         ElementType.MODULE,
+         ElementType.TYPE})
+ // CLASS retention will hopefully be sufficient for the purposes at hand
+@Retention(RetentionPolicy.CLASS)
+// *Not* @Documented
+public @interface PreviewFeature {
+    /**
+     * Name of the preview feature the annotated API is associated
+     * with.
+     */
+    public Feature feature();
+
+    public boolean essentialAPI() default false;
+
+    public enum Feature {
+        SWITCH_EXPRESSIONS,
+        TEXT_BLOCKS;
+    }
+}