HDFS-14222. Make ThrottledAsyncChecker constructor public. Contributed by Arpit Agarwal.

(cherry picked from commit 6f0756fc0e43b785d3dee72a669997d934b57e4c)

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

@@ -88,7 +88,7 @@ public class ThrottledAsyncChecker<K, V> implements AsyncChecker<K, V> {
    */
   private final Map<Checkable, LastCheckResult<V>> completedChecks;
 
-  ThrottledAsyncChecker(final Timer timer,
+  public ThrottledAsyncChecker(final Timer timer,
                         final long minMsBetweenChecks,
                         final long diskCheckTimeout,
                         final ExecutorService executorService) {