Add warning in documentation as an argument for setting headers should be not key value array, but indexed array. Or make according changes in withHeader method

[vasymus]

After spending several hours on finding the bug, decide to use raw https://www.php.net/manual/ru/ref.curl.php

And found out that in the first time working with your library i just put headers wrong

Instead of correct way:

$response->withHeaders([
     'X-Requested-With: XMLHttpRequest',
    'Content-Type: application/x-www-form-urlencoded',
]);

i did wrong way:

$response->withHeaders([
     'X-Requested-With' => 'XMLHttpRequest',
    'Content-Type' => 'application/x-www-form-urlencoded',
]);

So, my proposition for you:
either put a warning in your documentation about headers (i know, you describe the right way, but maybe you should put some more highlighted description)
or you could rewrite you methods in vendor/ixudra/curl/src/Builder.php
public function withHeader
and
public function withHeaders

for example

    public function withHeader($header)
    {
        if (is_array($header)) $header = implode(": ", $header);
        $this->curlOptions[ 'HTTPHEADER' ][] = $header;
        return $this;
    }

and

    public function withHeaders(array $headers)
    {
        $h = [];
        foreach ($headers as $key => $value) {
            if (!is_numeric($key)) {
                $value = "$key: $value";
            }
            $h[] = $value;
        }
        $this->curlOptions[ 'HTTPHEADER' ] = array_merge(
            $this->curlOptions[ 'HTTPHEADER' ], $h
        );
        return $this;
    }

[Jan Oris]

Hi @vasymus thanks for letting me know. An argument could be made for either case, of course, and I understand what you're saying. Since the point of this package is increased clarity and ease of use, I fully agree with your proposal. I'll make the necessary changes some time this weekend

[vasymus]

Thanks @elimentz ! :-)

[Jan Oris]

Now available in version 6.18.0! I only changed the withHeaders() method, as it seems very unlikely to me that the withHeader() method will be used incorrectly