Make use of Optional more idiomatic

Change-Id: I42b3261169e7cb8408f46c5831f72115f77fd779
diff --git a/core/net/src/main/java/org/onosproject/net/driver/impl/DriverManager.java b/core/net/src/main/java/org/onosproject/net/driver/impl/DriverManager.java
index 53a9a68..c16f558 100644
--- a/core/net/src/main/java/org/onosproject/net/driver/impl/DriverManager.java
+++ b/core/net/src/main/java/org/onosproject/net/driver/impl/DriverManager.java
@@ -148,7 +148,7 @@
                 .filter(d -> matches(d, mfr, hw, sw)).findFirst();
 
         // If no matching driver is found, return default.
-        return optional.isPresent() ? optional.get() : drivers.get(DEFAULT);
+        return optional.orElse(drivers.get(DEFAULT));
     }
 
     // Matches the given driver using ERE matching against the given criteria.