HDFS-16497. EC: Add param comment for liveBusyBlockIndices with HDFS-14768. Contributed by caozhiqiang.

(cherry picked from commit 37650ced81964efe7a9ea45bf505af96b8035d53)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java

@@ -2396,6 +2396,10 @@ public class BlockManager implements BlockStatsMXBean {
    *                    replicas of the given block.
    * @param liveBlockIndices List to be populated with indices of healthy
    *                         blocks in a striped block group
+   * @param liveBusyBlockIndices List to be populated with indices of healthy
+   *                             blocks in a striped block group in busy DN,
+   *                             which the recovery work have reached their
+   *                             replication limits
    * @param priority integer representing replication priority of the given
    *                 block
    * @return the array of DatanodeDescriptor of the chosen nodes from which to