Use lambda expression to simplify statements

Change-Id: Ib8ddac6e93327ade9d42984d8eba66be7047d051
diff --git a/apps/test/demo/src/main/java/org/onosproject/demo/DemoInstaller.java b/apps/test/demo/src/main/java/org/onosproject/demo/DemoInstaller.java
index 27d1ca9..a408e69 100644
--- a/apps/test/demo/src/main/java/org/onosproject/demo/DemoInstaller.java
+++ b/apps/test/demo/src/main/java/org/onosproject/demo/DemoInstaller.java
@@ -393,13 +393,8 @@
         }
 
         private Predicate<? super Host> hasLocalMaster() {
-            return new Predicate<Host>() {
-                @Override
-                public boolean apply(Host host) {
-                    return mastershipService.getLocalRole(
-                            host.location().deviceId()).equals(MastershipRole.MASTER);
-                }
-            };
+            return host -> mastershipService.getLocalRole(
+                    host.location().deviceId()).equals(MastershipRole.MASTER);
         }