YARN-5132. Exclude generated protobuf sources from YARN Javadoc build. (Subru Krishnan via kasha)

(cherry picked from commit f5ff05cc8a67c125717261392c996136ba66785b)

hadoop-yarn-project/hadoop-yarn/pom.xml

@@ -68,6 +68,13 @@
           </properties>
         </configuration>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-javadoc-plugin</artifactId>
+        <configuration>
+          <excludePackageNames>org.apache.hadoop.yarn.proto</excludePackageNames>
+        </configuration>
+      </plugin>
     </plugins>
   </build>