Using Paging 3 to paginate a list with a startRecord and an endRecord

Question

I am using paging 3 and cannot find my use case in the available tutorials. basically I paste is the example i find in the documentation and in all the tutorials on line, basically backend.searchUsers(query, nextPageNumber) does not fit my case I have just to call backend.fetchAList(userId,startRecord,endRecord) so basically I need to ask to the back end to giving to me only a specific range of pages, let's say I want 16 items per time, I guess I should ask startRecord:0 endRecord:15 then I do not know how if user scrolls at the end of the list I should ask startRecord:16 endRecord:31 and so on, till the end of the list. How can I achieve that with Paging3?

EDIT: I am assuming that my approach should be like I mention above my use case is: as user I want to retrieve a list with PaginatedData to fill my adapter, loading the list gradually so that the use scroll a certain number of pages and then new ones are retrieved from the back end, with the condition that the back end has these fields: startRecord: Int; endRecord:Int, hasNextItems: Boolean, List, totalItems: Int

class ExamplePagingSource(
    val backend: ExampleBackendService,
    val query: String
) : PagingSource<Int, User>() {
  override suspend fun load(
    params: LoadParams<Int>
  ): LoadResult<Int, User> {
    try {
      // Start refresh at page 1 if undefined.
      val nextPageNumber = params.key ?: 1
      val response = backend.searchUsers(query, nextPageNumber)
      return LoadResult.Page(
        data = response.users,
        prevKey = null, // Only paging forward.
        nextKey = response.nextPageNumber
      )
    } catch (e: Exception) {
      // Handle errors in this block and return LoadResult.Error if it is an
      // expected error (such as a network failure).
    }
  }

  override fun getRefreshKey(state: PagingState<Int, User>): Int? {
    // Try to find the page key of the closest page to anchorPosition, from
    // either the prevKey or the nextKey, but you need to handle nullability
    // here:
    //  * prevKey == null -> anchorPage is the first page.
    //  * nextKey == null -> anchorPage is the last page.
    //  * both prevKey and nextKey null -> anchorPage is the initial page, so
    //    just return null.
    return state.anchorPosition?.let { anchorPosition ->
      val anchorPage = state.closestPageToPosition(anchorPosition)
      anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
    }
  }
}