AbstractBackEndHierarchicalDataProvider HierarchicalQuery getLimit () allwa

Good day!
I use TreeGrid component with LazyLod from backend. I extends may dataprovider class from AbstractBackEndHierarchicalDataProvider<Company, Void> There is function:

protected Stream<Company> fetchChildrenFromBackEnd(HierarchicalQuery<Company, Void> query) {

May be there is a bug. When ever I scroll the grid, query.getOffset() allways is 0 but query.getLimit() allways is equal to record count.
Please help me understand how query.getLimit() return the value which equals to record count.