Partitioned DocumentTree primitive

Change-Id: I7e1712e1b7103756f9c8c6ad7118f8da5bb0fa2f
diff --git a/core/api/src/main/java/org/onosproject/store/service/DocumentPath.java b/core/api/src/main/java/org/onosproject/store/service/DocumentPath.java
index a5e1eaa..333cbb1 100644
--- a/core/api/src/main/java/org/onosproject/store/service/DocumentPath.java
+++ b/core/api/src/main/java/org/onosproject/store/service/DocumentPath.java
@@ -45,6 +45,9 @@
     private static String pathSeparator = DEFAULT_SEPARATOR;
     private static String pathSeparatorRE = DEFAULT_SEPARATOR_RE;
 
+    /** Root document tree path. */
+    public static final DocumentPath ROOT = DocumentPath.from("root");
+
     private final List<String> pathElements = Lists.newArrayList();
 
     /**