Cleaning up Javadocs in core-ui classes.
Added common constants to AbstractCellFormatter.

Change-Id: Ie20ea62f059646e7d6c7f3660dd60a60c40532fe
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiClusterMember.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiClusterMember.java
index d8803ab..f0aae01 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiClusterMember.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiClusterMember.java
@@ -43,7 +43,7 @@
      * topology instance and the specified controller node instance.
      *
      * @param topology parent topology containing this cluster member
-     * @param cnode    underlying controller node.
+     * @param cnode    underlying controller node
      */
     public UiClusterMember(UiTopology topology, ControllerNode cnode) {
         this.topology = topology;
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiDevice.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiDevice.java
index c05d27b..04eaab0 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiDevice.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiDevice.java
@@ -101,7 +101,7 @@
      * Returns the identifier of the region to which this device belongs.
      * This will be null if the device does not belong to any region.
      *
-     * @return region identity
+     * @return region ID
      */
     public RegionId regionId() {
         return regionId;
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiLayer.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiLayer.java
deleted file mode 100644
index 30d16f6..0000000
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiLayer.java
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Copyright 2016-present Open Networking Laboratory
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.onosproject.ui.model.topo;
-
-/**
- * Designates the logical layer of the network that an element belongs to.
- */
-public enum UiLayer {
-    PACKET, OPTICAL;
-
-    /**
-     * Returns the default layer (for those elements that do not explicitly
-     * define which layer they belong to).
-     *
-     * @return default layer
-     */
-    public static UiLayer defaultLayer() {
-        return PACKET;
-    }
-}
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiLinkId.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiLinkId.java
index 3bde82a..ca85fb2 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiLinkId.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiLinkId.java
@@ -49,7 +49,7 @@
         B_TO_A
     }
 
-    static final String CP_DELIMITER = "~";
+    private static final String CP_DELIMITER = "~";
     static final String ID_PORT_DELIMITER = "/";
 
     private final RegionId regionA;
@@ -236,7 +236,8 @@
         ConnectPoint src = link.src();
         ConnectPoint dst = link.dst();
         if (src == null || dst == null) {
-            throw new NullPointerException("null src or dst connect point: " + link);
+            throw new NullPointerException(
+                    "null src or dst connect point: " + link);
         }
 
         ElementId srcId = src.elementId();
diff --git a/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegionLink.java b/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegionLink.java
index 45a27b9..afc6777 100644
--- a/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegionLink.java
+++ b/core/api/src/main/java/org/onosproject/ui/model/topo/UiRegionLink.java
@@ -36,7 +36,7 @@
      * link identifier is one that has region IDs as source and destination.
      *
      * @param topology parent topology
-     * @param id       canonicalized link identifier
+     * @param id       canonicalized link ID
      * @throws IllegalArgumentException if the link ID is not region-region
      */
     public UiRegionLink(UiTopology topology, UiLinkId id) {