Fix creation of hashmap mapping with a zero cost

A cost of 0.0 was interpreted as a False value, making the check think
the cost argument was missing.

Change-Id: I5f86540221b80667fc63b8b54659092c637b7353
Story: 2009047
Task: 42814

cloudkittyclient/v1/rating/hashmap.py

@@ -172,7 +172,7 @@ class HashmapManager(base.BaseManager):
         :param value: Value of the mapping
         :type value: str
         """
-        if not kwargs.get('cost'):
+        if kwargs.get('cost') is None:
             raise exc.ArgumentRequired("'cost' argument is required")
         if not kwargs.get('value'):
             if not kwargs.get('service_id'):

releasenotes/notes/fix-zero-cost-mapping-7a4247cf1c6815f8.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Fixes creation of hashmap mappings with a zero cost.