src/vs/workbench/services/dialogs/browser/abstractFileDialogService.ts/AbstractFileDialogService/getFileSystemSchema
class AbstractFileDialogService:	protected getFileSystemSchema(options: { availableFileSystems?: readonly string[]; defaultUri?: URI }): string {
		return options.availableFileSystems && options.availableFileSystems[0] || this.getSchemeFilterForWindow(options.defaultUri?.scheme);
	}