When nesting SplitPanes with two or more items (which one of them the TreeView or ListView).
If setting divider to 1 (or 0 positon related) and then setting in previous value TreeView is not rendering.
SplitPanel
 |-SomeItem
 |-Anchor
    |-TreeView
if change position divider manualy after that treeView rendering.
if change to another position (saved + 0.1) it works correct.

there code
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    private Boolean itemsOpen;
    private Double value;

    public void onClickHideShowButton(ActionEvent actionEvent) {
        if (itemsOpen == null) {
            itemsOpen = Math.round(splitPane.getDividers().get(0).getPosition() * 10) != 10;
        }
        if (itemsOpen) {
            //save divide position
            value = splitPane.getDividers().get(0).getPosition();
            splitPane.getDividers().get(0).setPosition(1);
            itemsOpen = false;
        } else {
            //load saved position
            splitPane.getDividers().get(0).setPosition(value);
            itemsOpen = true;
        }
    }