HADOOP-14905. Fix javadocs issues in Hadoop HDFS-NFS. Contributed by Mukul Kumar Singh.

hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/nfs3/Nfs3Utils.java

@@ -88,6 +88,8 @@ public class Nfs3Utils {
   /**
    * HDFS directory size is always zero. Try to return something meaningful
    * here. Assume each child take 32bytes.
+   * @param childNum number of children of the directory
+   * @return total size of the directory
    */
   public static long getDirSize(int childNum) {
     return (childNum + 2) * 32;
@@ -122,6 +124,9 @@ public class Nfs3Utils {
 
   /**
    * Send a write response to the netty network socket channel
+   * @param channel channel to which the buffer needs to be written
+   * @param out xdr object to be written to the channel
+   * @param xid transaction identifier
    */
   public static void writeChannel(Channel channel, XDR out, int xid) {
     if (channel == null) {