Make optional the validation of filters

This fix covers the cases where it's required to be
flexible in the validation of unknown filters.

Change-Id: I1becad77d48556181c5667ad06b2971b8b8517b2
Partially-Implements: blueprint adopt-oslo-versioned-objects-for-db
Closes-Bug: #1622672
diff --git a/neutron/tests/tempest/api/test_subnetpools.py b/neutron/tests/tempest/api/test_subnetpools.py
index 5bd222f..634cd60 100644
--- a/neutron/tests/tempest/api/test_subnetpools.py
+++ b/neutron/tests/tempest/api/test_subnetpools.py
@@ -390,3 +390,7 @@
     @test.idempotent_id('82a13efc-c18f-4249-b8ec-cec7cf26fbd6')
     def test_list_no_pagination_limit_0(self):
         self._test_list_no_pagination_limit_0()
+
+    @test.idempotent_id('27feb3f8-40f4-4e50-8cd2-7d0096a98682')
+    def test_list_validation_filters(self):
+        self._test_list_validation_filters()