Description: Adds the Yetus annotations (https://yetus.apache.org)
Author: Emmanuel Bourg <ebourg@apache.org>
Forwarded: not-needed
--- /dev/null
+++ b/src/java/main/org/apache/yetus/audience/InterfaceAudience.java
@@ -0,0 +1,74 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.yetus.audience;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Annotation to inform users of a package, class or method's intended audience.
+ * Currently the audience can be {@link Public}, {@link LimitedPrivate} or
+ * {@link Private}. <br>
+ * All public classes must have InterfaceAudience annotation. <br>
+ * <ul>
+ * <li>Public classes that are not marked with this annotation must be
+ * considered by default as {@link Private}.</li>
+ *
+ * <li>External applications must only use classes that are marked
+ * {@link Public}. Avoid using non public classes as these classes
+ * could be removed or change in incompatible ways.</li>
+ *
+ * <li>Some projects may choose to give special consideration to related
+ * projects. Such consideration can be done by using the {@link LimitedPrivate}
+ * annotation with a named set of projects.</li>
+ *
+ * <li> Methods may have a different annotation that it is more restrictive
+ * compared to the audience classification of the class. Example: A class
+ * might be {@link Public}, but a method may be {@link LimitedPrivate}
+ * </li></ul>
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+public class InterfaceAudience {
+  /**
+   * Intended for use by any project or application.
+   */
+  @Documented
+  @Retention(RetentionPolicy.RUNTIME)
+  public @interface Public {};
+
+  /**
+   * Intended only for the project(s) specified in the annotation.
+   * For example, "Hadoop Common", "HDFS", "MapReduce", "ZooKeeper", "HBase".
+   */
+  @Documented
+  @Retention(RetentionPolicy.RUNTIME)
+  public @interface LimitedPrivate {
+    String[] value();
+  };
+
+  /**
+   * Intended for use only within a given project.
+   */
+  @Documented
+  @Retention(RetentionPolicy.RUNTIME)
+  public @interface Private {};
+
+  private InterfaceAudience() {} // Audience can't exist on its own
+}
--- /dev/null
+++ b/src/java/main/org/apache/yetus/audience/InterfaceStability.java
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.yetus.audience;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+import org.apache.yetus.audience.InterfaceAudience.LimitedPrivate;
+import org.apache.yetus.audience.InterfaceAudience.Private;
+import org.apache.yetus.audience.InterfaceAudience.Public;
+
+/**
+ * Annotation to inform users of how much to rely on a particular package,
+ * class or method not changing over time. Currently the stability can be
+ * {@link Stable}, {@link Evolving} or {@link Unstable}. <br>
+ *
+ * <ul><li>All classes that are annotated with {@link Public} or
+ * {@link LimitedPrivate} must have InterfaceStability annotation. </li>
+ * <li>Classes that are {@link Private} are to be considered unstable unless
+ * a different InterfaceStability annotation states otherwise.</li>
+ * <li>Incompatible changes must not be made to classes marked as stable.</li>
+ * </ul>
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+public class InterfaceStability {
+  /**
+   * Can evolve while retaining compatibility for minor release boundaries.;
+   * can break compatibility only at major release (ie. at m.0).
+   */
+  @Documented
+  @Retention(RetentionPolicy.RUNTIME)
+  public @interface Stable {};
+
+  /**
+   * Evolving, but can break compatibility at minor release (i.e. m.x)
+   */
+  @Documented
+  @Retention(RetentionPolicy.RUNTIME)
+  public @interface Evolving {};
+
+  /**
+   * No guarantee is provided as to reliability or stability across any
+   * level of release granularity.
+   */
+  @Documented
+  @Retention(RetentionPolicy.RUNTIME)
+  public @interface Unstable {};
+}