Fix compilation problem on some versions of the JVM

Change-Id: I3f2c7ad8fbcd228c7eeb0a2125fcbdbfcb572bd9
diff --git a/apps/events/src/main/java/org/onosproject/events/EventsCommand.java b/apps/events/src/main/java/org/onosproject/events/EventsCommand.java
index c6f15de..67f8981 100644
--- a/apps/events/src/main/java/org/onosproject/events/EventsCommand.java
+++ b/apps/events/src/main/java/org/onosproject/events/EventsCommand.java
@@ -218,7 +218,8 @@
 
         } else if (event instanceof TopologyEvent) {
             TopologyEvent topoEvent = (TopologyEvent) event;
-            List<Event> reasons = MoreObjects.firstNonNull(topoEvent.reasons(), ImmutableList.of());
+            List<Event> reasons = MoreObjects.firstNonNull(topoEvent.reasons(),
+                                                           ImmutableList.<Event>of());
             Topology topo = topoEvent.subject();
             String summary = String.format("(d=%d,l=%d,c=%d)",
                                            topo.deviceCount(),