Add a header to an existing collection of headers.
string $header Header name to add:
string $value Value of the header:
Overrides MessageInterface::addHeader
public function addHeader($header, $value) {
$key = strtolower($header);
if (!isset($this->headers[$key])) {
$this->headers[$key] = new Header($header, $value);
}
else {
$this->headers[$key]
->add($value, $header);
}
$this
->changedHeader($key);
return $this;
}