[CORD-3008] Before removing OLT check that no subscribers are using it

Change-Id: I7f3d0f9d552a74a05c3f447cbb35b75f29595c87
diff --git a/samples/olt_device.yaml b/samples/olt_device.yaml
index 8277a9b..93c905f 100644
--- a/samples/olt_device.yaml
+++ b/samples/olt_device.yaml
@@ -17,8 +17,6 @@
 tosca_definitions_version: tosca_simple_yaml_1_0
 imports:
   - custom_types/oltdevice.yaml
-  - custom_types/onudevice.yaml
-  - custom_types/ponport.yaml
   - custom_types/voltservice.yaml
 description: Create a simulated OLT Device in VOLTHA
 topology_template:
diff --git a/samples/pon_port.yaml b/samples/pon_port.yaml
index d35d0b8..a97d315 100644
--- a/samples/pon_port.yaml
+++ b/samples/pon_port.yaml
@@ -35,10 +35,20 @@
     pon_port:
       type: tosca.nodes.PONPort
       properties:
-        name: test_olt_port_1
+        name: test_pon_port_1
         port_no: 2
         s_tag: 222
       requirements:
         - olt_device:
             node: device#olt
             relationship: tosca.relationships.BelongsToOne
+
+    onu:
+      type: tosca.nodes.ONUDevice
+      properties:
+        serial_number: BRCM1234
+        vendor: Broadcom
+      requirements:
+        - pon_port:
+            node: pon_port
+            relationship: tosca.relationships.BelongsToOne