Make DiscreteResourceCodecs package private

Change-Id: I4db1440729ce78e4fd64d3fe43e942f6d39e779c
(cherry picked from commit 078b6b81)

@@ -23,7 +23,7 @@ import org.onosproject.net.resource.DiscreteResourceCodec;
  * Codec for MplsLabel.
  */
 @Beta
-public final class MplsCodec implements DiscreteResourceCodec<MplsLabel> {
+final class MplsCodec implements DiscreteResourceCodec<MplsLabel> {
     @Override
     public int encode(MplsLabel resource) {
         return resource.toInt();

@@ -23,7 +23,7 @@ import org.onosproject.net.resource.DiscreteResourceCodec;
  * Codec for Vlan.
  */
 @Beta
-public final class VlanCodec implements DiscreteResourceCodec<VlanId> {
+final class VlanCodec implements DiscreteResourceCodec<VlanId> {
     @Override
     public int encode(VlanId resource) {
         return resource.toShort();