sortText
A string that should be used when comparing this item with other items. When falsy the label is used.
Note that sortText is only used for the initial ordering of completion items. When having a leading word (prefix) ordering is based on how well completions match that prefix and the initial ordering is only used when completions match equally well. The prefix is defined by the {@linkcode CompletionItem.range range}-property and can therefore be different for each completion.