Exclude alien Port from Edge ports

- Remote end of inter-domain link can contain Port
  not managed by local cluster. Exclude them.

Change-Id: I74cd705d98d16ffefd14242ac273272bb1e6677d
diff --git a/core/api/src/test/java/org/onosproject/net/device/DeviceServiceAdapter.java b/core/api/src/test/java/org/onosproject/net/device/DeviceServiceAdapter.java
index bc9411d..7d31d0f 100644
--- a/core/api/src/test/java/org/onosproject/net/device/DeviceServiceAdapter.java
+++ b/core/api/src/test/java/org/onosproject/net/device/DeviceServiceAdapter.java
@@ -103,7 +103,10 @@
 
     @Override
     public Port getPort(DeviceId deviceId, PortNumber portNumber) {
-        return null;
+        return getPorts(deviceId).stream()
+                   .filter(port -> deviceId.equals(port.element().id()))
+                   .filter(port -> portNumber.equals(port.number()))
+                   .findFirst().orElse(null);
     }
 
     @Override