src/vs/workbench/api/common/extHostComments.ts/ExtHostCommentsImpl/createCommentController
class ExtHostCommentsImpl:		createCommentController(extension: IExtensionDescription, id: string, label: string): vscode.CommentController {
			const handle = ExtHostCommentsImpl.handlePool++;
			const commentController = new ExtHostCommentController(extension, handle, id, label);
			this._commentControllers.set(commentController.handle, commentController);

			const commentControllers = this._commentControllersByExtension.get(ExtensionIdentifier.toKey(extension.identifier)) || [];
			commentControllers.push(commentController);
			this._commentControllersByExtension.set(ExtensionIdentifier.toKey(extension.identifier), commentControllers);

			return commentController.value;
		}