HADOOP-10896. Update compatibility doc to capture visibility of un-annotated classes/ methods. (kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1613543 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -621,6 +621,9 @@ Release 2.5.0 - UNRELEASED
 
     HADOOP-10782. Fix typo in DataChecksum class. (Jingguo Yao via suresh)
 
+    HADOOP-10896. Update compatibility doc to capture visibility of 
+    un-annotated classes/ methods. (kasha)
+
   OPTIMIZATIONS
 
     HADOOP-10674. Improve PureJavaCrc32 performance and use java.util.zip.CRC32

hadoop-common-project/hadoop-common/src/site/apt/Compatibility.apt.vm

@@ -72,10 +72,13 @@ Apache Hadoop Compatibility
     * Private-Stable APIs can change across major releases,
     but not within a major release.
 
+    * Classes not annotated are implicitly "Private". Class members not
+    annotated inherit the annotations of the enclosing class.
+
     * Note: APIs generated from the proto files need to be compatible for
-rolling-upgrades. See the section on wire-compatibility for more details. The
-compatibility policies for APIs and wire-communication need to go
-hand-in-hand to address this.
+    rolling-upgrades. See the section on wire-compatibility for more details.
+    The compatibility policies for APIs and wire-communication need to go
+    hand-in-hand to address this.
 
 ** Semantic compatibility