Create constructors with zero argument for serialization

Change-Id: I503197a2dcfe1b71dc6a82d4c2ca4512465200c5
diff --git a/core/api/src/main/java/org/onosproject/net/newresource/DefaultResource.java b/core/api/src/main/java/org/onosproject/net/newresource/DefaultResource.java
index 5d0efe4..1db5eb7 100644
--- a/core/api/src/main/java/org/onosproject/net/newresource/DefaultResource.java
+++ b/core/api/src/main/java/org/onosproject/net/newresource/DefaultResource.java
@@ -44,6 +44,12 @@
         this.resource = checkNotNull(resource);
     }
 
+    // for serialization
+    private DefaultResource() {
+        this.subject = null;
+        this.resource = null;
+    }
+
     @Override
     public S subject() {
         return subject;
diff --git a/core/api/src/main/java/org/onosproject/net/newresource/DefaultResourceAllocation.java b/core/api/src/main/java/org/onosproject/net/newresource/DefaultResourceAllocation.java
index 0b496a8..06b6dda 100644
--- a/core/api/src/main/java/org/onosproject/net/newresource/DefaultResourceAllocation.java
+++ b/core/api/src/main/java/org/onosproject/net/newresource/DefaultResourceAllocation.java
@@ -47,6 +47,13 @@
         this.consumer = consumer;
     }
 
+    // for serialization
+    private DefaultResourceAllocation() {
+        this.subject = null;
+        this.resource = null;
+        this.consumer = null;
+    }
+
     @Override
     public S subject() {
         return subject;