Finalize markdown tree tooltip and resolveTreeItem

Fixes #100741

src/vs/vscode.d.ts

@@ -8809,6 +8809,25 @@ declare module 'vscode' {
 		 * @return Parent of `element`.
 		 */
 		getParent?(element: T): ProviderResult<T>;
+
+		/**
+		 * Called only on hover to resolve the [TreeItem](#TreeItem.tooltip) property if it is undefined.
+		 * Only properties that were undefined can be resolved in `resolveTreeItem`.
+		 * Functionality may be expanded later to include being called to resolve other missing
+		 * properties on selection and/or on open.
+		 *
+		 * Will only ever be called once per TreeItem.
+		 *
+		 * *Note* that this function is called when tree items are already showing in the UI.
+		 * Because of that, no property that changes the presentation (label, description, command, etc.)
+		 * can be changed.
+		 *
+		 * @param element The object associated with the TreeItem
+		 * @param item Undefined properties of `item` should be set then `item` should be returned.
+		 * @return The resolved tree item or a thenable that resolves to such. It is OK to return the given
+		 * `item`. When no result is returned, the given `item` will be used.
+		 */
+		resolveTreeItem?(item: TreeItem, element: T): ProviderResult<TreeItem>;
 	}
 
 	export class TreeItem {
@@ -8848,7 +8867,7 @@ declare module 'vscode' {
 		/**
 		 * The tooltip text when you hover over this item.
 		 */
-		tooltip?: string | undefined;
+		tooltip?: string | MarkdownString | undefined;
 
 		/**
 		 * The [command](#Command) that should be executed when the tree item is selected.

src/vs/vscode.proposed.d.ts

@@ -943,29 +943,6 @@ declare module 'vscode' {
 	//#endregion
 
 	//#region Tree View: https://github.com/microsoft/vscode/issues/61313
-
-	// https://github.com/microsoft/vscode/issues/100741
-	export interface TreeDataProvider<T> {
-		/**
-		 * Called only on hover to resolve the TreeItem2#tooltip property if it is undefined.
-		 * Only properties that were undefined can be resolved in `resolveTreeItem`.
-		 * Will only ever be called once per TreeItem.
-		 * Functionality may be expanded later to include being called to resolve other missing
-		 * properties on selection and/or on open.
-		 *
-		 * @param element
-		 * @param item Undefined properties of `item` should be set then `item` should be returned.
-		 */
-		resolveTreeItem?(item: TreeItem2, element: T): ProviderResult<TreeItem2>;
-	}
-
-	export class TreeItem2 extends TreeItem {
-		/**
-		 * Content to be shown when you hover over the tree item.
-		 */
-		tooltip?: string | MarkdownString | /* for compilation */ any;
-	}
-
 	export interface TreeView<T> extends Disposable {
 		reveal(element: T | undefined, options?: { select?: boolean, focus?: boolean, expand?: boolean | number }): Thenable<void>;
 	}

src/vs/workbench/api/common/extHostTreeViews.ts

@@ -17,7 +17,6 @@ import { TreeItemCollapsibleState, ThemeIcon, MarkdownString as MarkdownStringTy
 import { isUndefinedOrNull, isString } from 'vs/base/common/types';
 import { equals, coalesce } from 'vs/base/common/arrays';
 import { ILogService } from 'vs/platform/log/common/log';
-import { checkProposedApiEnabled } from 'vs/workbench/services/extensions/common/extensions';
 import { IExtensionDescription } from 'vs/platform/extensions/common/extensions';
 import { MarkdownString } from 'vs/workbench/api/common/extHostTypeConverters';
 import { IMarkdownString } from 'vs/base/common/htmlContent';
@@ -182,7 +181,7 @@ type TreeData<T> = { message: boolean, element: T | Root | false };
 
 interface TreeNode extends IDisposable {
 	item: ITreeItem;
-	extensionItem: vscode.TreeItem2;
+	extensionItem: vscode.TreeItem;
 	parent: TreeNode | Root;
 	children?: TreeNode[];
 }
@@ -569,13 +568,12 @@ class ExtHostTreeView<T> extends Disposable {
 
 	private getTooltip(tooltip?: string | vscode.MarkdownString): string | IMarkdownString | undefined {
 		if (MarkdownStringType.isMarkdownString(tooltip)) {
-			checkProposedApiEnabled(this.extension);
 			return MarkdownString.from(tooltip);
 		}
 		return tooltip;
 	}
 
-	private createTreeNode(element: T, extensionTreeItem: vscode.TreeItem2, parent: TreeNode | Root): TreeNode {
+	private createTreeNode(element: T, extensionTreeItem: vscode.TreeItem, parent: TreeNode | Root): TreeNode {
 		const disposable = new DisposableStore();
 		const handle = this.createHandle(element, extensionTreeItem, parent);
 		const icon = this.getLightIconPath(extensionTreeItem);
@@ -604,7 +602,7 @@ class ExtHostTreeView<T> extends Disposable {
 		};
 	}
 
-	private getThemeIcon(extensionTreeItem: vscode.TreeItem2): ThemeIcon | undefined {
+	private getThemeIcon(extensionTreeItem: vscode.TreeItem): ThemeIcon | undefined {
 		return extensionTreeItem.iconPath instanceof ThemeIcon ? extensionTreeItem.iconPath : undefined;
 	}