Generalize the MultiValuedTimestamp.

Change-Id: I691730d59f440778856afd0e4808ba775eccba0a
diff --git a/core/net/src/main/java/org/onosproject/net/device/impl/DeviceManager.java b/core/net/src/main/java/org/onosproject/net/device/impl/DeviceManager.java
index c99f874..e8cccf4 100644
--- a/core/net/src/main/java/org/onosproject/net/device/impl/DeviceManager.java
+++ b/core/net/src/main/java/org/onosproject/net/device/impl/DeviceManager.java
@@ -15,17 +15,6 @@
  */
 package org.onosproject.net.device.impl;
 
-import static com.google.common.base.Preconditions.checkNotNull;
-import static org.onosproject.net.MastershipRole.*;
-import static org.onlab.util.Tools.namedThreads;
-import static org.slf4j.LoggerFactory.getLogger;
-
-import java.util.List;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.TimeUnit;
-
-
 import com.google.common.collect.Lists;
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
@@ -65,6 +54,18 @@
 import org.onosproject.net.provider.AbstractProviderService;
 import org.slf4j.Logger;
 
+import java.util.List;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.onlab.util.Tools.namedThreads;
+import static org.onosproject.net.MastershipRole.MASTER;
+import static org.onosproject.net.MastershipRole.NONE;
+import static org.onosproject.net.MastershipRole.STANDBY;
+import static org.slf4j.LoggerFactory.getLogger;
+
 /**
  * Provides implementation of the device SB & NB APIs.
  */
@@ -234,7 +235,7 @@
         log.debug("Checking mastership");
         for (Device device : getDevices()) {
             final DeviceId deviceId = device.id();
-            log.debug("Checking device {}", deviceId);
+            log.trace("Checking device {}", deviceId);
 
             if (!isReachable(deviceId)) {
                 continue;