YARN-9069. Fix SchedulerInfo#getSchedulerType for custom schedulers. Contributed by Bilwa S T.

(cherry picked from commit 07142f54a8c7f70857e99c041f3a2a5189c809b5)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/dao/SchedulerInfo.java

@@ -53,6 +53,8 @@ public class SchedulerInfo {
       this.schedulerName = "Fair Scheduler";
     } else if (rs instanceof FifoScheduler) {
       this.schedulerName = "Fifo Scheduler";
+    } else {
+      this.schedulerName = rs.getClass().getSimpleName();
     }
     this.minAllocResource = new ResourceInfo(rs.getMinimumResourceCapability());
     this.maxAllocResource = new ResourceInfo(rs.getMaximumResourceCapability());