$this->assertSame($element['#attached']['drupalSettings'], $expected_js_settings, '#attached is modified; both the original JavaScript setting and the ones added by each placeholder #lazy_builder callback exist.');
// GET request: validate cached data.
$this->assertSame($element['#attached']['drupalSettings'], $expected_js_settings, '#attached is modified; both the original JavaScript setting and the ones added by each placeholder #lazy_builder callback exist.');