src/language-js/printer-estree.js/printDecorators
function printDecorators(path, options, print) {
  const node = path.getValue();
  return group(
    concat([
      join(line, path.map(print, "decorators")),
      hasNewlineBetweenOrAfterDecorators(node, options) ? hardline : line,
    ])
  );
}