Resolve unchecked cast warnings introduced with #28892

server/src/main/java/org/elasticsearch/action/support/master/AcknowledgedRequest.java

@@ -92,7 +92,7 @@ public abstract class AcknowledgedRequest<Request extends MasterNodeRequest<Requ
     @Override
     public boolean equals(Object o) {
         if (super.equals(o)) {
-            AcknowledgedRequest<Request> that = (AcknowledgedRequest<Request>) o;
+            AcknowledgedRequest<?> that = (AcknowledgedRequest<?>) o;
             return Objects.equals(timeout, that.timeout);
         }
         return false;

server/src/main/java/org/elasticsearch/action/support/master/MasterNodeRequest.java

@@ -86,7 +86,7 @@ public abstract class MasterNodeRequest<Request extends MasterNodeRequest<Reques
         if (o == null || getClass() != o.getClass()) {
             return false;
         }
-        MasterNodeRequest<Request> that = (MasterNodeRequest<Request>) o;
+        MasterNodeRequest<?> that = (MasterNodeRequest<?>) o;
         return Objects.equals(masterNodeTimeout, that.masterNodeTimeout);
     }