code/libraries/joomlatools/library/http/message/headers.php
public function offsetSet($key, $value)
    {
        $key = strtr(strtolower($key), '_', '-');

        $this->_data[$key] = $value;
    }
public function offsetSet($key, $value)
    {
        $key = strtr(strtolower($key), '_', '-');

        $this->_data[$key] = $value;
    }
public function offsetSet ( $ key , $ value ) { $ key = strtr ( strtolower ( $ key ) , '_' , '-' ) ; $ this -> _data [ $ key ] = $ value ; }
Set a value by key

@param   string  $key   The key name
@param   mixed   $value The value for the key
@return  void
Set a value by key