Embed VolumeSource in v1beta3 and internal.

examples/cassandra/v1beta3/cassandra-controller.yaml

@@ -38,6 +38,5 @@ spec:
               name: data
       volumes: 
         - name: data
-          source: 
-            emptyDir: {}
+          emptyDir: {}
 

examples/mysql-wordpress-pd/v1beta3/mysql.yaml

@@ -33,10 +33,8 @@ spec:
               mountPath: /var/lib/mysql
       volumes:
         - name: mysql-persistent-storage
-          source:
-            # emptyDir: {}
-            persistentDisk:
-              # This GCE PD must already exist.
-              pdName: mysql-disk
-              fsType: ext4
+          persistentDisk:
+            # This GCE PD must already exist.
+            pdName: mysql-disk
+            fsType: ext4
 

examples/mysql-wordpress-pd/v1beta3/wordpress.yaml

@@ -30,10 +30,8 @@ spec:
               mountPath: /var/www/html
       volumes:
         - name: wordpress-persistent-storage
-          source:
-            # emptyDir: {}
-            persistentDisk:
-              # This GCE PD must already exist.
-              pdName: wordpress-disk
-              fsType: ext4
+          persistentDisk:
+            # This GCE PD must already exist.
+            pdName: wordpress-disk
+            fsType: ext4