Write
class WriteConflictException(val conflicting: List<DocId>, val key: String? = null) : DelvaException(source)
An insert conflicts with the state it would take effect on. Nothing of the insert is visible and nothing was deleted. Nothing is wrong with the document itself: read the current state and try again. Either:
a replace (JsonStore.replace, InsertSource.replaces) named documents that aren't visible when it would take effect: deleted, perhaps replaced by another call, or never stored; key is then null; or
in a store with CreationOptions.documentKey, the document's key is the key of a visible document the insert doesn't replace, which conflicting names; JsonStore.upsert replaces it instead.