private function loadBehavior($package)
    {
        if (isset($package['type']) && $package['type'] == self::BEHAVIOR_PACKAGE_TYPE) {

            // find propel behavior information
            if (isset($package['extra'])) {
                $extra = $package['extra'];

                if (isset($extra['name']) && isset($extra['class'])) {
                    return [
                        'name' => $extra['name'],
                        'class' => $extra['class'],
                        'package' => $package['name']
                    ];
                } else {
                    throw new BuildException(sprintf('Cannot read behavior name and class from package %s', $package['name']));
                }
            }
        }

        return null;
    }