--- /dev/null	2018-06-17 23:18:20.806999507 +0800
+++ new/src/share/classes/jdk/jfr/Experimental.java	2019-01-29 10:58:40.620286326 +0800
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2016, 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.jfr;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation that signifies that an element is experimental and may change
+ * without notice.
+ * <p>
+ * Clients that visualize Flight Recorder events should <em>not</em> show the
+ * events or fields annotated with the {@code Experimental} annotation by
+ * default. This annotation allows event producers the freedom to try out new
+ * events without committing to them.
+ * <p>
+ * Clients may provide a check box (for example, in a preference page) where a
+ * user can opt-in to display experimental data. If the user decide to do so,
+ * the user interface should mark experimental events or fields so users can
+ * distinguish them from non-experimental events.
+ * <p>
+ * This annotation is inherited.
+ *
+ * @since 9
+ */
+@MetadataDefinition
+@Label("Experimental")
+@Description("Element is not to be shown to a user by default")
+@Inherited
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.FIELD, ElementType.TYPE })
+public @interface Experimental {
+}