aristidb/aws — pull request #127 by jonsterling (2014-08-22 17:43:18+00:00)
Title: Fix CondOp JSON rendering for nullary conditional operators

`AttributeValueList` must only be rendered when it is to contain at least one element. Rendering an empty `AttributeValueList` will result in a 500 error; this occurs when using a nullary conditional operator such as `IsNull` or `NotNull`.