src/Http/Formatting/HttpHeaderParser.php
public function isMultipart(HttpHeaders $headers): bool
    {
        $contentType = null;
        $headers->tryGetFirst('Content-Type', $contentType);

        return preg_match("/multipart\//i", $contentType) === 1;
    }
public function isMultipart(HttpHeaders $headers): bool
    {
        $contentType = null;
        $headers->tryGetFirst('Content-Type', $contentType);

        return preg_match("/multipart\//i", $contentType) === 1;
    }
Gets whether or not the message is a multipart message

@param HttpHeaders $headers The headers to parse
@return bool True if the request is a multipart message, otherwise false
@throws RuntimeException Thrown if the content type header's hash key could not be calculated