Symfony version(s) affected

6.1.6

Description

When sending a request with symfony http-client and the body in the options array is an array, the content-type is always set to application/x-www-form-urlencoded even if I explicitly set another content-type.

I need to set charset on the content type like this Content-Type: application/x-www-form-urlencoded; charset=utf-8, but it gets overridden.

How to reproduce

$response = $this->client->request('POST', '/create', [
  'headers' => [
    'Content-Type' => 'application/x-www-form-urlencoded; charset=utf-8'
  ],
  'body' => ['key' => 'value']
]);
$response->getContent();

// We can see here that the Content-Type header is "application/x-www-form-urlencoded" and not "application/x-www-form-urlencoded; charset=utf-8"
$debugInfo = $response->getInfo('debug')

Possible Solution

Remove these lines or add a check if the header is already set.

https://github.com/symfony/http-client/blob/c8c887f4813370550147afd27d9eb8a8523e53b2/HttpClientTrait.php#L100-L102

Additional Context

Looks like this was introduced in #45812 but I do not understand the reasoning behind doing it. I should be able to set the header I want. at least be able to set charset.

A workaround for me is to normalize the body into a string my self, but I should not have to do that in my opinion.