extensions/configuration-editing/src/configurationEditingMain.ts/registerExtensionsCompletionsInWorkspaceConfigurationDocument
function registerExtensionsCompletionsInWorkspaceConfigurationDocument(): vscode.Disposable {
	return vscode.languages.registerCompletionItemProvider({ pattern: '**/*.code-workspace' }, {
		provideCompletionItems(document, position, _token) {
			const location = getLocation(document.getText(), document.offsetAt(position));
			if (location.path[0] === 'extensions' && location.path[1] === 'recommendations') {
				const range = getReplaceRange(document, location, position);
				const extensionsContent = <IExtensionsContent>parse(document.getText())['extensions'];
				return provideInstalledExtensionProposals(extensionsContent && extensionsContent.recommendations || [], '', range, false);
			}
			return [];
		}
	});
}