Minor fixes in DatabaseProxy

Change-Id: I2e1ac92a80f652acc324337383dba526e510f353
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultDatabaseState.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultDatabaseState.java
index 2a37e53..18ae2c4 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultDatabaseState.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultDatabaseState.java
@@ -27,7 +27,6 @@
 import java.util.stream.Collectors;
 import java.util.Set;
 
-import org.apache.commons.lang3.tuple.Pair;
 import org.onosproject.cluster.NodeId;
 import org.onosproject.store.service.DatabaseUpdate;
 import org.onosproject.store.service.Transaction;
@@ -112,7 +111,7 @@
     }
 
     @Override
-    public int size(String mapName) {
+    public int mapSize(String mapName) {
       return getMap(mapName).size();
     }
 
@@ -186,7 +185,7 @@
         return ImmutableSet.copyOf(getMap(mapName)
                 .entrySet()
                 .stream()
-                .map(entry -> Pair.of(entry.getKey(), entry.getValue()))
+                .map(entry -> Maps.immutableEntry(entry.getKey(), entry.getValue()))
                 .collect(Collectors.toSet()));
     }