Change the APIs to instantiate Resource and ResourceId

Now, DiscreteResource/DiscreteResourceId is provided by DiscreteFactory.
Similarly, ContinuousResource/ContinuousResourceId is provided by
ContinuousFactory. These factory instances can be obtained by static
factory method such as Resource.discrete(...) or Resource.continuous(...).

Change-Id: Ic94f7336c0e1f74cf2dddcac899de300362aff3e
diff --git a/core/api/src/main/java/org/onosproject/net/newresource/DiscreteFactory.java b/core/api/src/main/java/org/onosproject/net/newresource/DiscreteFactory.java
new file mode 100644
index 0000000..b285641
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/newresource/DiscreteFactory.java
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2016 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.net.newresource;
+
+import com.google.common.annotations.Beta;
+
+/**
+ * Factory class for discrete-type resource related instances.
+ */
+@Beta
+public final class DiscreteFactory {
+    private final DiscreteResourceId id;
+
+    /**
+     * Create an instance with the specified resource ID.
+     *
+     * @param id resource ID that is associated with the resource related instances
+     *           which will be created from this instance
+     */
+    DiscreteFactory(DiscreteResourceId id) {
+        this.id = id;
+    }
+
+    /**
+     * Returns the resource ID for discrete-type.
+     *
+     * @return discrete-type resource ID
+     */
+    public DiscreteResourceId id() {
+        return id;
+    }
+
+    /**
+     * Returns the resource for discrete-type.
+     *
+     * @return discrete-type resource
+     */
+    public DiscreteResource resource() {
+        return new DiscreteResource(id);
+    }
+}