schema: automatically cast scalar value to list values (#28175)

bijoe/schemas.py

@@ -88,6 +88,8 @@ class Base(object):
                 kls = types[key]
                 if isinstance(kls, list):
                     kls = kls[0]
+                    if not isinstance(value, list):
+                        value = [value]
                     if hasattr(kls, 'from_json'):
                         value = [kls.from_json(v) for v in value]
                     else: