In the EzPublishLegacyBundle/LegacyResponse/LegacyResponseManager.php file, mapHeaders() method, it's possible that the $header is empty or malformed what will result in unnecessary undefined index and undefined offset warnings

public function mapHeaders( array $headers, Response $response )
{
    foreach ( $headers as $header )
    {
        $headerArray = explode( ": ", $header, 2 );
        $headerName = strtolower( $headerArray[0] );
        $headerValue = $headerArray[1];

It's important that these warnings are handled and to check if the indexes exist before trying to execute any code.