Issue #3524626 by kristiaanvandeneynde: Renderer::doRender() and...

      return $return;

    }

    // Only when we're in a root (non-recursive) Renderer::render() call,

    // placeholders must be processed, to prevent breaking the render cache in

    // case of nested elements with #cache set.

    // Only when rendering the root do placeholders have to be processed. If we

    // were to replace them while rendering cacheable nested elements, their

    // cacheable metadata would still bubble all the way up the render tree,

    // effectively making the use of placeholders pointless.

    $this->replacePlaceholders($elements);

    return $elements['#markup'];

    }

    $context->push(new BubbleableMetadata());

    // Set the bubbleable rendering metadata that has configurable defaults, if:

    // - this is the root call, to ensure that the final render array definitely

    //   has these configurable defaults, even when no subtree is render cached.

    // - this is a render cacheable subtree, to ensure that the cached data has

    // Set the bubbleable rendering metadata that has configurable defaults if

    // this is a render cacheable subtree, to ensure that the cached data has

    // the configurable defaults (which may affect the ID and invalidation).

    if (isset($elements['#cache']['keys'])) {

      $required_cache_contexts = $this->rendererConfig['required_cache_contexts'];