set* methods for fields of type List do not cause the specified value to be persisted unless deltas is false

[killergerbah]

Given a field with this configuration:

            {
              "name": "stringList",
              "dynamoName": "stringList",
              "type": "List",
              "elementType": "String"
            }

The generated setStringList method will set the in-memory state of the *Updates object, but the list is not actually persisted since only the list adds are used when generating the Dynamo DB update expression. On the other hand, setting deltas: false will cause values passed to setStringList to be persisted. It may be less confusing if setStringList is not generated at all in the case of deltas: true.