The length of the text to be replaced if the remainder of the identifier
containing the cursor is to be replaced when the suggestion is applied
(that is, the number of characters in the existing identifier).
The offset of the start of the text to be replaced. This will be different
from the offset used to request the completion suggestions if there was a
portion of an identifier before the original offset. In particular, the
replacementOffset will be the offset of the beginning of said identifier.
The completion suggestions being reported. This list is filtered by the
already existing prefix, and sorted first by relevance, and (if the same)
by the suggestion text. The list will have at most maxResults items. If
the user types a new keystroke, the client is expected to either do local
filtering (when the returned list was complete), or ask the server again
(if isIncomplete was true).