introduce temporary API to migrate a project view tree to a new model AsyncTreeModel.setRootImmediately(StructureTreeModel.getRootImmediately)

platform/platform-impl/src/com/intellij/ui/tree/AsyncTreeModel.java

@@ -866,4 +866,15 @@ public final class AsyncTreeModel extends AbstractTreeModel implements Disposabl
       }
     }
   }
+
+  /**
+   * @deprecated do not use
+   */
+  @Deprecated
+  public void setRootImmediately(@NotNull Object object) {
+    Node node = new Node(object, false);
+    node.insertPath(new TreePath(object));
+    tree.root = node;
+    tree.map.put(object, node);
+  }
 }

platform/platform-impl/src/com/intellij/ui/tree/StructureTreeModel.java

@@ -294,4 +294,15 @@ public class StructureTreeModel extends AbstractTreeModel implements Disposable,
       return child instanceof Node && isNodeChild((Node)child) ? getChildren().indexOf(child) : -1;
     }
   }
+
+  /**
+   * @deprecated do not use
+   */
+  @Deprecated
+  public final Object getRootImmediately() {
+    if (!root.isValid()) {
+      root.set(getValidRoot());
+    }
+    return root.get();
+  }
 }