groupBy property
Sections: the key of the section a record belongs to, such as its day or its status. Each run of records with the same key gets one header above it, so sort the query by the same field: an unsorted list repeats a header wherever its key comes back. Records from Load more join the last section when they share its key. While the list scrolls by itself the current header stays pinned at the top until the next one pushes it away; with scrollsWithPage headers sit inline. Separators are drawn between rows of a section, never around a header. Vertical lists only.
Implementation
final String Function(KoolbaseRecord record)? groupBy;