Use lambda instead of anonymous inner class

Change-Id: I5b2b93e82ec50296af66970ac518d7e0e8a14177

@@ -16,7 +16,6 @@
 package org.onosproject.store.device.impl;
 
 import com.google.common.base.Function;
-import com.google.common.base.Predicate;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Maps;
@@ -286,13 +285,7 @@ public class GossipDeviceStore
     @Override
     public Iterable<Device> getAvailableDevices() {
         return FluentIterable.from(getDevices())
-                .filter(new Predicate<Device>() {
-
-                    @Override
-                    public boolean apply(Device input) {
-                        return isAvailable(input.id());
-                    }
-                });
+                .filter(input -> isAvailable(input.id()));
     }
 
     @Override