This setting defaults to false so there is no need to set it unless we want it to be true. This makes it easy to see at a glace which backends support this, and matches the existing behaviour of other fields such as `AllowAtAtStartOfIdentifier`, `AllowQuestionAtStartOfIdentifier`, `UseAssignmentForEHBegin` and `AllowAtInName`. These are all only ever set to true in subclasses, never false.