A mutation to create a new Item on a specific Roadmap.
As with in-app behaviour, you must specify a summary (Item Name) when creating a new Item. Given that Items are associated with a single, specific roadmap, a valid roadmapID must also be specified in order to create a new Item. All other fields are optional.
An Item can only have actual date(s) (a single date or Start and End Dates) or a bucket time, but not both.
If the intent is to create a sub-Item as part of an Item hierarchy, a valid parentItemID must be specified. All in-app restrictions pertaining to sub-Items will also be enforced via the API (eg. maximum number of allowed sub-Items in a given family).