code: public function diffUploadChangeset($xml, $id)
  	{
  		$token = $this->oauth->getToken();
  
  		// Set parameters.
  		$parameters = array(
  			'oauth_token' => $token['key'],
  		);
  
  		// Set the API base
  		$base = 'changeset/' . $id . '/upload';
  
  		// Build the request path.
  		$path = $this->getOption('api.url') . $base;
  
  		$header['Content-Type'] = 'text/xml';
  
  		// Send the request.
  		$response = $this->oauth->oauthRequest($path, 'POST', $parameters, $xml, $header);
  
  		$xmlString = simplexml_load_string($response->body);
  
  		return $xmlString->diffResult;
  	}
docs: Method to upload a diff to a changeset
  
  @param   string   $xml  Diff data to upload
  @param   integer  $id   Identifier of the changeset
  
  @return  array  The XML response of result
  
  @since   1.0