In order to convert a String value to a Date, The `DefaultConversionService`
uses the constructor `java.util.Date(java.lang.String)` behind the scene
(from `org.springframework.core.convert.support.ObjectToObjectConverter.convert`).
This constructor throws a `java.lang.IllegalArgumentException` for values in
CET timezone, for example: "Thu Jan 04 09:05:50 CET 2018".
This commit updates the failing test to use a fixed timezone (UTC).
Resolves BATCH-2668