Add nodetool cmd to print hinted handoff window

Patch by Varun Gupta; Reviewed by Jeff Jirsa for CASSANDRA-13728

CHANGES.txt

@@ -1,4 +1,5 @@
 4.0
+ * Add nodetool cmd to print hinted handoff window (CASSANDRA-13728)
  * Checksum sstable metadata (CASSANDRA-13321, CASSANDRA-13593)
  * Add result set metadata to prepared statement MD5 hash calculation (CASSANDRA-10786)
  * Refactor GcCompactionTest to avoid boxing (CASSANDRA-13941)

src/java/org/apache/cassandra/tools/NodeTool.java

@@ -147,7 +147,8 @@ public class NodeTool
                 FailureDetectorInfo.class,
                 RefreshSizeEstimates.class,
                 RelocateSSTables.class,
-                ViewBuildStatus.class
+                ViewBuildStatus.class,
+                HandoffWindow.class
         );
 
         Cli.CliBuilder<Runnable> builder = Cli.builder("nodetool");

src/java/org/apache/cassandra/tools/nodetool/HandoffWindow.java

@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.cassandra.tools.nodetool;
+
+import io.airlift.airline.Command;
+import org.apache.cassandra.tools.NodeProbe;
+import org.apache.cassandra.tools.NodeTool;
+
+@Command(name = "handoffwindow", description = "Print current hinted handoff window")
+public class HandoffWindow extends NodeTool.NodeToolCmd
+{
+    @Override
+    public void execute(NodeProbe probe)
+    {
+        System.out.println(String.format("Hinted handoff window is %s",
+                                         probe.getMaxHintWindow()));
+    }
+}