Pull Request for Issue #39495 .

Summary of Changes

Fixes linked bug

Testing Instructions

In a webservice plugin (either custom or in a core one in the core add the following lines to the onBeforeApiRoute event (i used the content webservice plugin - but any will do)

        \JFactory::getApplication()->addFormatMap('application/ld+json', 'jsonld');
        $router->addRoute(
            new Route(['GET'], 'v1/format', '', [], ['format' => ['application/vnd.api+json', 'application/ld+json'], 'component' => 'com_content'])
        );

Then in the libraries/src/Application/ApiApplication.php add var_dump($this->input->get('format'), $this->input->get('option'));die; after this foreach loop (both before and after testing)

Generate a Bearer token and curl the url e.g. curl -H "Authentication: Bearer <bearer_token>" -H "Accept: application/ld+json" http://localhost/joomla-cms/api/index.php/v1/format

Actual result BEFORE applying this Pull Request

        array(2) {
          [0]=>
          string(22) "applicationvnd.apijson"
          [1]=>
          string(17) "applicationldjson"
        }
        string(11) "com_content"

Expected result AFTER applying this Pull Request

        string(7) "jsonld"
        string(11) "com_content"

i.e. the second dump (the component) is unchanged and the former (the format) now contains the Joomla format and not the array of possible options from the plugin

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed