Command to list optical connectivities

Change-Id: Ic1b69c04cbc51fd384711de73abe91f1b0d11abb
diff --git a/apps/newoptical/src/main/java/org/onosproject/newoptical/api/OpticalPathService.java b/apps/newoptical/src/main/java/org/onosproject/newoptical/api/OpticalPathService.java
index 8da5d54..4e95224 100644
--- a/apps/newoptical/src/main/java/org/onosproject/newoptical/api/OpticalPathService.java
+++ b/apps/newoptical/src/main/java/org/onosproject/newoptical/api/OpticalPathService.java
@@ -21,8 +21,10 @@
 import org.onosproject.net.ConnectPoint;
 import org.onosproject.net.Link;
 import org.onosproject.net.Path;
+import org.onosproject.newoptical.OpticalConnectivity;
 
 import java.time.Duration;
+import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
 
@@ -68,4 +70,11 @@
      * @return list of link that compose a path. empty if ID is invalid.
      */
     Optional<List<Link>> getPath(OpticalConnectivityId id);
+
+    /**
+     * Lists collection of known OpticalConnectivity.
+     *
+     * @return collection of OpticalConnectivity
+     */
+    Collection<OpticalConnectivity> listConnectivity();
 }