Use lambda expression to simplify statements

Change-Id: Ib8ddac6e93327ade9d42984d8eba66be7047d051
diff --git a/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java b/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
index 6345643..973db49 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/device/impl/GossipDeviceStore.java
@@ -15,7 +15,6 @@
  */
 package org.onosproject.store.device.impl;
 
-import com.google.common.base.Function;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Maps;
@@ -564,13 +563,10 @@
                 final DeviceDescriptions descs = device.get(providerId);
                 List<PortDescription> mergedList =
                         FluentIterable.from(portDescriptions)
-                                .transform(new Function<PortDescription, PortDescription>() {
-                                    @Override
-                                    public PortDescription apply(PortDescription input) {
-                                        // lookup merged port description
-                                        return descs.getPortDesc(input.portNumber()).value();
-                                    }
-                                }).toList();
+                                .transform(input ->
+                                    // lookup merged port description
+                                    descs.getPortDesc(input.portNumber()).value()
+                                ).toList();
                 merged = new Timestamped<>(mergedList, newTimestamp);
             }