lib/classes/Swift/Mime/SimpleHeaderSet.php
public function listAll()
    {
        $headers = $this->headers;
        if ($this->canSort()) {
            uksort($headers, [$this, 'sortHeaders']);
        }

        return array_keys($headers);
    }
public function listAll()
    {
        $headers = $this->headers;
        if ($this->canSort()) {
            uksort($headers, [$this, 'sortHeaders']);
        }

        return array_keys($headers);
    }
public function listAll ( ) { $ headers = $ this -> headers ; if ( $ this -> canSort ( ) ) { uksort ( $ headers , [ $ this , 'sortHeaders' ] ) ; } return array_keys ( $ headers ) ; }
Return the name of all Headers.

@return array
Return the name of all Headers .