fix #1010 Tree expand/shrink function does not work reliable

Author: vegegoku

domino-ui/src/main/java/org/dominokit/domino/ui/collapsible/Collapsible.java

@@ -17,7 +17,6 @@
 
 import static java.util.Objects.isNull;
 import static java.util.Objects.nonNull;
-import static org.dominokit.domino.ui.utils.Domino.*;
 import static org.dominokit.domino.ui.utils.ElementsFactory.elements;
 
 import elemental2.dom.Element;

domino-ui/src/main/java/org/dominokit/domino/ui/collapsible/TreeHeightCollapseStrategy.java

@@ -207,11 +207,15 @@ private void collapseElement(Element element) {
     if (dui_transition_none.isAppliedTo(node)) {
       node.setAttribute(DUI_COLLAPSED, "true");
       node.setCssProperty(this.heightVar, node.getAttribute(DUI_COLLAPSED_HEIGHT) + "px");
+      handlers.onCollapseCompleted().run();
+      collapsing = false;
     } else {
       DomGlobal.requestAnimationFrame(
           timestamp -> {
             node.setAttribute(DUI_COLLAPSED, "true");
             node.setCssProperty(this.heightVar, node.getAttribute(DUI_COLLAPSED_HEIGHT) + "px");
+            handlers.onCollapseCompleted().run();
+            collapsing = false;
           });
     }
   }

domino-ui/src/main/java/org/dominokit/domino/ui/tree/TreeNode.java

@@ -26,10 +26,7 @@
 import static org.dominokit.domino.ui.utils.Domino.span;
 import static org.dominokit.domino.ui.utils.Domino.ul;
 
-import elemental2.dom.Element;
-import elemental2.dom.EventListener;
-import elemental2.dom.HTMLAnchorElement;
-import elemental2.dom.HTMLLIElement;
+import elemental2.dom.*;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;