TYPO3 Core

Due to two colliding injects in WidgetRequestHandler the AjaxWidget functionality is completely broken.

After #73018 there are two injects setting requestBuilder within WidgetRequestHandler.

    /**
     * @param \TYPO3\CMS\Extbase\Mvc\Web\RequestBuilder $requestBuilder
     */
    public function injectWidgetRequestBuilder(\TYPO3\CMS\Fluid\Core\Widget\WidgetRequestBuilder $requestBuilder)
    {
        $this->requestBuilder = $requestBuilder;
    }

    /**
     * @param \TYPO3\CMS\Extbase\Mvc\Web\RequestBuilder $requestBuilder
     */
    public function injectRequestBuilder(\TYPO3\CMS\Extbase\Mvc\Web\RequestBuilder $requestBuilder)
    {
        $this->requestBuilder = $requestBuilder;
    }

First the local function "injectWidgetRequestBuilder()" is called and after that the inherited function "injectRequestBuilder()" is called.
Naturally, the inherited function resets the requestBuilder to something that cannot handle a widgetRequest, thus breaking Ajax Autocomplete in fluid.