some interface changes to flow and packet
diff --git a/core/api/src/main/java/org/onlab/onos/net/packet/PacketProviderRegistry.java b/core/api/src/main/java/org/onlab/onos/net/packet/PacketProviderRegistry.java
new file mode 100644
index 0000000..86df510
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/net/packet/PacketProviderRegistry.java
@@ -0,0 +1,10 @@
+package org.onlab.onos.net.packet;
+
+import org.onlab.onos.net.provider.ProviderRegistry;
+
+/**
+ * Abstraction of an infrastructure packet provider registry.
+ */
+public interface PacketProviderRegistry
+extends ProviderRegistry<PacketProvider, PacketProviderService> {
+}