1 /*
2  * Copyright 2017, OpenCensus Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *     http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package io.opencensus.common;
18 
19 import java.lang.annotation.Documented;
20 import java.lang.annotation.ElementType;
21 import java.lang.annotation.Retention;
22 import java.lang.annotation.RetentionPolicy;
23 import java.lang.annotation.Target;
24 
25 /**
26  * Indicates a public API that can change at any time, and has no guarantee of API stability and
27  * backward-compatibility.
28  *
29  * <p>Usage guidelines:
30  *
31  * <ol>
32  *   <li>This annotation is used only on public API. Internal interfaces should not use it.
33  *   <li>After OpenCensus has gained API stability, this annotation can only be added to new API.
34  *       Adding it to an existing API is considered API-breaking.
35  *   <li>Removing this annotation from an API gives it stable status.
36  * </ol>
37  *
38  * @since 0.8
39  */
40 @Internal
41 @Retention(RetentionPolicy.SOURCE)
42 @Target({
43   ElementType.ANNOTATION_TYPE,
44   ElementType.CONSTRUCTOR,
45   ElementType.FIELD,
46   ElementType.METHOD,
47   ElementType.PACKAGE,
48   ElementType.TYPE
49 })
50 @Documented
51 public @interface ExperimentalApi {
52   /**
53    * Context information such as links to discussion thread, tracking issue etc.
54    *
55    * @since 0.8
56    */
value()57   String value() default "";
58 }
59