code: public function getAuthenticationData( $method ) {
  		if ( ! $this->supportsAuthentication( $method ) ) {
  			return null;
  		}
  
  		$authentication = $this->getSupportedAuthentication();
  		return $authentication[ $method ];
  	}
docs: Get method-specific data for the given authentication method.
  
  @param string $method Authentication method to get data for.
  @return mixed Method-specific data if available, null if not supported.