Bugfix in ListProperty(), correctly handle list values of length 1

lib/src/db/annotations.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of gcloud.db;
 
 /// Annotation used to mark dart classes which can be stored into datastore.
 ///
 /// The `Kind` annotation on a class as well as other `Property` annotations on
 /// fields or getters of the class itself (and any of it's superclasses) up to
@@ skipping 240 matching lines @@
     for (var entry in value) {
        if (!subProperty.validate(db, entry)) return false;
     }
     return true;
   }
 
   Object encodeValue(ModelDB db, Object value) {
     if (value == null) return null;
     List list = value;
     if (list.length == 0) return null;
-    if (list.length == 1) return list[0];
+    if (list.length == 1) return subProperty.encodeValue(db, list[0]);
     return list.map(
         (value) => subProperty.encodeValue(db, value)).toList();
   }
 
   Object decodePrimitiveValue(ModelDB db, Object value) {
     if (value == null) return [];
-    if (value is! List) return [value];
+    if (value is! List) return [subProperty.decodePrimitiveValue(db, value)];
     return (value as List)
         .map((entry) => subProperty.decodePrimitiveValue(db, entry))
         .toList();
   }
 }
 
 /// A convenience [Property] for list of strings.
 class StringListProperty extends ListProperty {
   const StringListProperty({String propertyName, bool indexed: true})
       : super(const StringProperty(),
               propertyName: propertyName, indexed: indexed);
 }