api and manager for statistic service

Change-Id: If00b8b43a2bd780ae3c05321697896290fb0f415
diff --git a/core/net/src/main/java/org/onlab/onos/net/statistic/impl/package-info.java b/core/net/src/main/java/org/onlab/onos/net/statistic/impl/package-info.java
new file mode 100644
index 0000000..cbe301c
--- /dev/null
+++ b/core/net/src/main/java/org/onlab/onos/net/statistic/impl/package-info.java
@@ -0,0 +1,4 @@
+/**
+ * Core subsystem for responding to statistical inquiries.
+ */
+package org.onlab.onos.net.statistic.impl;
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