fix javadoc

Author: LiuGuH

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/DataTransferProtocol.java

@@ -248,7 +248,7 @@ void blockGroupChecksum(StripedBlockInfo stripedBlockInfo,
    * @param targetBlk the block to be writted.
    * @param targetBlockToken security token for accessing targetBlk.
    * @param targetDatanode the target datnode which sourceBlk will copy to as targetBlk.
-   * @throws IOException throws IOException
+   * @throws IOException if an I/O error occurred
    */
   void copyBlockCrossNamespace(ExtendedBlock sourceBlk,
       Token<BlockTokenIdentifier> sourceBlockToken, ExtendedBlock targetBlk,

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DirectoryScanner.java

@@ -461,6 +461,7 @@ void shutdown() {
 
   /**
    * Reconcile differences between disk and in-memory blocks
+   * @throws IOException if an I/O error occurred
    */
   @VisibleForTesting
   public void reconcile() throws IOException {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/FsDatasetSpi.java

@@ -717,7 +717,7 @@ default void setLastDirScannerFinishTime(long time) {}
    * @param dstBlock
    *          the destination block to which the srcBlock needs to be copied to
    * @throws IOException
-   *          throws IOException
+   *          if an I/O error occurred
    */
   void hardLinkOneBlock(ExtendedBlock srcBlock, ExtendedBlock dstBlock)
       throws IOException;